Dissertations / Theses on the topic 'Mold coatings'

The interfacial heat transfer coefficient is an important variable regarding the subject of metal castings. The error associated with the experimental temperature data must be dealt with appropriately so that they do not significantly affect the resulting interfacial heat transfer coefficient. The systematic and random errors are addressed using a combination of three-dimensional finite element modeling and the matrix transform method, respectively. Experimentally obtained A356 permanent mold casting data was used to estimate the interfacial heat transfer coefficient corresponding to common industrial mold coatings.

Созданы новые составы покрытий на основе отходов производства для защиты изложниц при разливке стали сифоном и сверху, характеризующиеся высокими показателями физико-механических свойств, эффективно защищающие рабочую поверхность изложниц от агрессивного воздействия стали и газов, обеспечивающие улучшение санитарно-гигиенические условия труда.
Created new coating compositions based waste products for the protection of molds for casting steel trap and above, characterized by high levels of physical and mechanical properties, effectively protects the work surface from aggressive mold steel and gas, providing improved sanitary conditions.

Thesis (Ph. D.)--Ohio State University, 2004.
Title from first page of PDF file. Document formatted into pages; contains xviii, 226 p. : ill. (some col.). Advisor: Jose M. Castro, Dept. of Industrial and Systems Engineering. Includes bibliographical references (p. 225-226).

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
Cherry tomato (Lycopersicon esculentum L.) fruit are higly perishable. The infection of cherry tomato fruit with the pathogenic fungi Aspergillus niger and Rhizopus stolonifer is associated with high postharvest losses and decreased quality during storage. This study evaluated the efficacy of an edible coating comprising chitosan (CHI; 4 mg/mL) and Origanum vulgare L. essential oil (OVEO; 1.25 μL/mL) for keeping the quality of cherry tomato fruit during storage at room (25 °C; 12 days) and cold (12 °C; 24 days) temperatures, considering the physical, physicochemical and sensory aspects. The minimum inhibitory concentrations (MIC) of CHI and OVEO were 4 mg/mL and 10 μL/mL respectively, against R. stolonifer and A. niger. The incorporation of CHI 4 mg/ml and OVEO 5 μL/mL, 2.5 μL/mL and 1.25 μL/mL in the growth media showed fungicidal effect and strongly inhibited the germination of spores, mycelial growth and sporulation of fungal strains test. CHI-OVEO coating reduced black mold and soft-rot incidence caused by these fungi in artificially contaminated cherry tomato fruit during storage at both temperatures. Fruit coated with CHI-OVEO showed higher firmness and lower weigth loss. CHI-OVEO coating delayed the decrease of lycopene, ascorbic and citric acid, glucose and fructose during storage at room or cold temperatures. Fruit coated with CHI-OVEO showed increased amounts of catechin, myricetin, caffeic and syringic acids at the end of storage. CHI-OVEO coating is a feasible treatment for keep the storage quality of cherry tomato fruit. These results indicate that the CHI-OVEO edible coating is a viable treatment for maintaining quality during storage cherry tomatoes.
Tomates cereja (Lycopersicon esculentum L.) são frutos altamente perecíveis. A contaminação destes frutos com os fungos patogênicos Aspergillus niger e Rhizopus stolonifer é associada à elevadas perdas pós-colheita e à redução da qualidade durante o armazenamento. Este estudo avaliou a eficácia de um revestimento comestível composto de quitosana (QUI; 4 mg/mL) e óleo essencial de Origanum vulgare L. (OEOV; 1.25 μL/mL) na manutenção da qualidade de frutos de tomate cereja durante o armazenamento em temperatura ambiente (25 °C; 12 dias) e refrigerada (12 °C; 24 dias) considerando os aspectos físicos, físico-químicos e sensoriais. A concentração inibitória mínima (CIM) da QUI e do OEOV foram 4 mg/mL e 10 μL/mL, respectivamente, contra R. stolonifer e A. niger. A incorporação de QUI a 4 mg/mL e OVEO a 5 μL/mL, 2,5 μL/mL e 1,25 μL/mL no meio de crescimento mostrou efeito fungicida e inibiu fortemente a germinação dos esporos, o crescimento micelial e esporulação das cepas teste. O revestimento de QUI-OEOV reduziu a incidência de bolor negro e podridão-mole causada por estes fungos em frutos de tomate cereja artificialmente contaminados durante o armazenamento em ambas as temperaturas estudadas. Frutos revestidos com QUI-OEOV mostraram maior firmeza e menor perda de peso. O revestimento de QUI-OEOV retardou a redução de licopeno, ácido ascórbico e cítrico, glicose e frutose durante o armazenamento em temperatura ambiente ou refrigerada. Ao final do armazenamento, os frutos revestidos com QUI-OEOV apresentaram maiores quantidades de catequina, miricetina, ácido cafeico e ácido siringico em comparação aos frutos não revestidos. Nos testes sensoriais, os frutos revestidos com QUI-OVEO receberam maiores escores para os atributos aparência, sabor e cor quando comparados aos frutos sem revestimento. Estes resultados indicam que o revestimento comestível de QUI-OEOV é um tratamento viável para manter a qualidade de tomates cereja durante o armazenamento.

Doutoramento em Engenharia Mecânica
A área do de metal duro encontra actualmente um vasto campo de aplicações e por esse motivo é considerada uma área estratégica do ponto de vista tecnológico e científico. Salientam-se neste âmbito, o corte por arranque de apara, as ferramentas de estampagem, o corte de chapa e ferramentas para resistência ao desgaste. Compreende-se assim o elevado número de publicações e projectos de I&D dedicados nos últimos anos ao aumento do tempo de vida e desempenho de ferramentas. É bem conhecido que alguns materiais utilizados na indústria de moldes (alumínios e suas ligas) ou na produção de eléctrodos para electroerosão de penetração (grafite, cobre e suas ligas) são de difícil maquinação. Por esse motivo, as ferramentas de corte apresentam, geralmente, um reduzido tempo de vida. Neste contexto, o recurso a ferramentas com diamante policristalino como material de revestimento tem sido geralmente adoptado, apesar dos elevados custos que lhes está associado. Além disso, o revestimento de ferramentas de metal duro com filmes de diamante encerra algumas dificuldades tecnológicas, nomeadamente a adesão ao substrato Estudos previamente realizados demonstram que a fase de nucleação é determinante para o controlo do tamanho de grão do filme O presente trabalho de doutoramento teve como principal objectivo desenvolver novas soluções tecnológicas para a deposição de filmes de diamante com elevadas taxas de nucleação. Para o efeito, desenvolveu-se a técnica de deposição química em fase vapor modulada no tempo com controlo de tamanho de grão (TMCVD-GC). Esta técnica pressupõe a combinação das técnicas usuais de TMCVD com fluxos críticos de gases conducentes à obtenção de uma mono camada com elevada taxa de nucleação. Deve salientarse que no caso de revestimentos de metal duro, a fraca adesão está relacionada com as tensões residuais com origem na enorme diferença entre coeficiente de expansão térmica do diamante e do metal duro e com o efeito grafitizante do cobalto. Os filmes produzidos por TMCVD foram testados em condições industriais de maquinação de grafite, por torneamento. Os mecanismos de desgaste inerentes ao processo foram objecto de análise. Foi testado o comportamento de dois “interlayer” (CrN e SiC) no processo de nucleação/crescimento de diamante e o desempenho do “interlayer” de carboneto de silício foi testado na maquinação de grafite. Finalmente procedeu-se à comparação do desempenho das ferramentas revestidas por TMCVD com o desempenho de ferramentas comercias de PCD.
Today, the cemented carbide has found wide application in different areas such as the cutting tools, the wear parts, and the metal forming tools. Therefore, the powder metallurgy of cemented carbides is considered as topic of major interest for the scientific community and the industry. Certainly this is the reason why in the past years were observed the increase of I&D projects with the purpose of increasing the performance and the tool life of the tools. It is well known that a few materials employed in the mould industry (aluminium alloys) or in the EDM (electrical discharge machines) electrodes are of difficult machining with high accuracy. Therefore, the tool life is in general very short. Consequently WC-Co tools coated with polycrystalline diamond tools are often employed for this application, despite its high cost. However, to obtain such coatings with high quality represents an enormous challenge, due to the lack of adhesion between the diamond film and the substrate. Previous studies have shown that proper control of the early nucleation stage of diamond crystallites is detrimental for the crystal grain size control. The main objective of the present work is to develop new technological solutions for the deposition of diamond films with high nucleation density. For that, it was been developed a technique based on the modulation of the gases, with time, during the chemical vapour deposition, namely TMCVD. This process enables not only the control of the crystal grain size of the coating (TMCVD-GC) but also a high nucleation density. The films grown by TMCVD were tested in industrial cutting conditions by dry turning of graphite. The wear mechanisms were identified and studied. It was studied two approaches of interlayer to prevent the negative effect of cobalt during the diamond grown, the silicon carbide (SiC) and the chromium nitrite (CrN). The behaviour of the SiC interlayer was tested during the dry turning of graphite. Finally, the performance of the diamond coatings was compared with the performance of commercial polycrystalline diamond tools, under the same cutting operations.

Разработаны научные основы осаждения жаростойких покрытий для защиты изложниц и на этой основе созданы новые покрытия стеклокерамического типа, обладающие высокозащитным действием, обеспечивающие повышение стойкости изложниц и улучшение качества материала.
The scientific bases for the deposition of heat-resistant coatings for the protection of molds have been developed, and new glass-ceramic-type coatings have been developed on this basis, which have a highly protective effect, which increase the resistance of molds and improve the quality of the material.

Thesis (MScAgric)--Stellenbosch University, 2012.
ENGLISH ABSTRACT: Green mould is a major citrus postharvest disease caused by a wound pathogen called Penicillium digitatum. Imazalil (IMZ) is the most important postharvest fungicide that is currently registered against green mould and blue mould, given its good protective and curative control and sporulation inhibition. Imazalil can be applied in drench, dip, spray and wax coating applications. Wax coatings improve the quality of the fruit during shelf life by limiting moisture loss and providing a shiny appearance. The primary objective of this study was to investigate the application of imazalil in wax coatings in citrus packhouses to control green mould and preserve fruit quality. The first aim of this study was to evaluate the protective and curative control and sporulation inhibition of IMZ sensitive and resistant isolates of P. digitatum following single IMZ application in wax coating and IMZ application in aqueous dip as well as wax coating. For single application, Valencia orange fruit was curatively or protectively treated with a carnauba-based coating into which IMZ at 3000 μg.mL-1 was mixed. For curative treatments, fruit was treated after 24 hour's incubation. Coating was applied at 0.6, 1.2 and 1.8 L.ton-1 of fruit on a commercial coating applicator. Untreated control and fruit treated with coating only showed up to 80% infection for both sensitive and resistant isolates. Imazalil in coating proved to have better protective than curative action against the sensitive isolate, while control of the resistant isolate was poor. Imazalil residue levels increased with increasing coating load (0.85 to 1.75 μg.g-1). For double application, clementine, satsuma, navel and Valencia orange fruit were used. Curative and protective control following dip only treatment (IMZ sulphate at 500 μg.mL-1 for 45 s and 90 s) was compared with coating only treatment (IMZ at 3000 μg.mL-1 at 1.8 L.ton-1), and double application comprising dip (45 s in IMZ sulphate at 500 μg.mL-1) followed by 2000 μg.mL-1 IMZ in coating at 0.6, 1.2 and 1.8 L.ton-1. Double application resulted in improved residue loading (0.85 to 2.06 μg.g-1) compared to dip only treatments (≈ 0.49 μg.g-1). Coating only resulted in the highest residue levels (1.82 to 7.09 μg.g-1), often exceeding the maximum residue limit of 5 μg.g-1. In all treatments, poor curative and protective control of the resistant isolate (<46% and <55%, respectively) and generally no sporulation inhibition was observed. For the sensitive isolate, dip only treatments resulted in better curative control (≈ 77%) than protective control (≈ 38%). Double application showed increased protective control with increasing wax load (≈ 69%) as well as good curative control (≈ 83%). Wax coating only treatment resulted in poor curative control (≈ 26%), but good protective control (≈ 80%). Sporulation inhibition of the sensitive isolate was generally improved in treatments that included IMZ application in the wax coating. This study successfully showed the additive benefits of double application of IMZ in the wax coating following an aqueous dip application. However, despite improved control of the sensitive isolate, the resistant isolate could not be controlled. The second objective of the study was to evaluate green mould control and quality preservation following IMZ application using different coating and brush types. The inoculation and treatment procedure was similar to the single application of wax coating described above but only the sensitive isolate of P. digitatum was used. Carnauba- or polyethylene-based wax coatings, including IMZ at 3000 μg.mL-1, was applied at a dosage of 0.6, 1.2 and 1.8 L.ton-1 using commercial horsehair or synthetic brushes. Fruit was either incubated for 4 days prior to wound infection ratings or stored at -0.5oC for 26 days and 7 days shelf life. Imazalil residues on fruit increased with increasing coating loads on navel oranges (1.31 to 3.32 μg.g-1) and Valencia oranges (3.22 to 6.00 μg.g-1). Better protective (≈ 58%) than curative control (≈ 14%) was observed, with horsehair brushes resulting in lower sporulation levels (≈ 59%) than synthetic brushes (≈ 64%). Fruit weight loss and firmness loss ratios relative to uncoated control fruit were significantly higher in fruit treated with polyethylene coating compared with carnauba coating treated fruit. However, polyethylene coating resulted in shinier fruit before and after storage, whereas carnauba coating resulted in lower shine ratios. Gaseous (CO2) exchange ratios remained similar for both coatings, but higher polyethylene coating loads (1.8 L.ton-1) resulted in off-tastes similar to the uncoated control fruit and higher than the ratings for carnauba. Scanning electron micrographs revealed an amorphous crystallised natural wax layer with uncovered stomatal pores on the surface of uncoated fruit. The thickness of the applied coating layer increased with increasing coating load. Coating layers following application with synthetic brushes at 1.2 L.ton-1 appeared to be thicker than when applied using horsehair brushes. This study indicated the effects of brush type on the distribution and polishing of the wax coating on the surface of the fruit and also the importance of cautious application of coating as under or over application may lead to poor results in terms of bio-efficacy, residue loading and fruit quality.
AFRIKAANSE OPSOMMING: Groenskimmel is 'n belangrike sitrus na-oessiekte, veroorsaak deur 'n wondpatogeen, genaamd Penicillium digitatum. Imazalil (IMZ) is die belangrikste na-oesfungisied wat tans teen groenskimmel geregistreer is, gegewe sy goeie beskermende en genesende beheer en sporulasie-inhibisie. Imazalil kan in bad-, doop-, spuit- en wakslaagbehandelings toegedien word. Wakslae behou die kwaliteit van die vrugte gedurende raklewe deur vogverlies te beperk en 'n glansvoorkoms te verskaf. Die primêre doel van hierdie studie was om die toediening van imazalil in wakslaagbehandelings in sitruspakhuise vir groenskimmel en vrugkwaliteit beheer te ondersoek. Die eerste doelwit van hierdie studie was om die beskermende en genesende beheer en sporulasie-inhibisie van IMZ sensitiewe en weerstandbiedende isolate van P. digitatum, gevolg deur enkel IMZ toediening in 'n wakslaagbehandeling, en IMZ toediening in 'n doop-, asook wakslaagbehandeling, te evalueer. Vir enkelltoediening is Valencia lemoenvrugte genesend of beskermend met 'n carnauba-gebaseerde wakslaag behandel, waarin IMZ teen 3000 μg.mL-1 gemeng is. Vir genesende behandelings is vrugte ná 24 uur inkubasie behandel. Wakslaagbehandeling is teen 0.6, 1.2 en 1.8 L.ton-1 vrugte op 'n semi-kommersiële paklyn toegedien. Onbehandelde kontrole en vrugte met waks behandel, het slegs tot 80% infeksie vir beide sensitiewe en weerstandbiedende isolate getoon. Imazalil in waks het beter beskermende as genesende aksie teen die sensitiewe isolaat getoon, terwyl beheer van die weerstandbiedende isolaat swak was. Imazalil residuvlakke het met toename in wakslading toegeneem (0.85 tot 1.75 μg.g-1). Vir dubbeltoediening is clementine, satsuma, navel en Valencia lemoenvrugte gebruik. Genesende en beskermende beheer van IMZ na enkel doopbehandeling (IMZ sulfaat teen 500 μg.mL-1 vir 45 s en 90 s), is met enkel waksbehandeling (IMZ teen 3000 μg.mL-1 teen 1.8 L.ton-1) vergelyk, asook dubbeltoediening bestaande uit doop (45 s in IMZ sulfaat teen 500 μg.mL-1), gevolg deur 2000 μg.mL-1 IMZ in waksbehandeling teen 0.6, 1.2 en 1.8 L.ton-1. Dubbeltoediening het verbeterde residulading (0.85 tot 2.06 μg.g-1) tot gevolg gehad, in vergelyking met enkel doopbehandelings (≈ 0.49 μg.g-1). Enkel waksbehandeling het die hoogste residuvlakke (1.82 tot 7.09 μg.g-1) tot gevolg gehad, wat dikwels die maksimum residu-limiet van 5 μg.g-1 oorskry het. In alle behandelings is swak genesende en beskermende beheer van die weerstandbiedende isolaat (<46% en <55%, onderskeidelik), en oor die algemeen, geen sporulasie-inhibisie, waargeneem. Vir die sensitiewe isolaat, het die enkel doopbehandelings beter genesende beheer (≈ 77%) in vergelyking met die beskermende beheer (≈ 38%) tot gevolg gehad. Dubbeltoediening het verhoogde beskermende beheer met toenemende wakslading (≈ 69%) getoon, asook goeie genesende beheer (≈ 83%). Enkel wakslaagbehandeling het swak genesende beheer (≈ 26%) tot gevolg gehad, maar goeie beskermende beheer (≈ 80%). Sporulasie-inhibisie van die sensitiewe isolaat was oor die algemeen beter in behandelings wat IMZ toediening in die wakslaag ingesluit het. Hierdie studie het suksesvol die toegevoegde voordele van dubbeltoediening van IMZ in doopbehandeling en wakslaag getoon. Ten spyte van die verbeterde beheer van die sensitiewe isolaat, kon die weerstandbiedende isolaat egter nie beheer word nie. Die tweede doelwit was om groenskimmelbeheer en behoud van kwaliteit te evalueer, volgende op IMZ toediening deur gebruik van verskillende waks- en borseltipes. Inokulasie- en behandelingsprosedure was soortgelyk aan die enkeltoediening van wakslaagbehandeling soos bo beskryf, maar slegs die sensitiewe isolaat van P. digitatum is gebruik. Carnauba- of poli-etileen-gebaseerde wakslae, insluitende IMZ teen 3000 μg.mL-1, is teen 'n dosis van 0.6, 1.2 en 1.8 L.ton-1 toegedien, deur die gebruik van kommersiële perdehaar of sintetiese borsels. Vrugte is óf vir 4 dae vóór wond-infeksie evaluering geïnkubeer, óf teen -0.5oC vir 26 dae en 7 dae raklewe gestoor. Imazalil residuvlakke op vrugte het met toenemende waksladings op navellemoene (1.31 tot 3.32 μg.g-1) en Valencia lemoene (3.22 tot 6.00 μg.g-1) toegeneem. Beter beskermende (≈ 58%) as genesende beheer (≈ 14%) is waargeneem, met perdehaar borsels wat laer sporulasievlakke (≈ 59%) tot gevolg gehad het, in vergelyking met sintetiese borsels (≈ 64%). Vruggewig- en fermheidsverlies verhoudings, relatief tot onbedekte kontrole vrugte, was betekenisvol hoër in vrugte wat met 'n poli-etileenwaks behandel is, in vergelyking met carnauba-waks behandelde vrugte. Poli-etileen waksbehandeling het egter blinker vrugte vóór en ná opberging tot gevolg gehad, terwyl canauba waksbehandeling laer blink verhoudings tot gevolg gehad het. Gas (CO2) uitruilverhoudings het dieselfde vir beide waksbehandelings gebly, maar hoër poli-etileen waksladings (1.8 L.ton-1) het tot afsmake soortgelyk aan die onbedekte kontrole vrugte gelei, en hoër as die evaluerings vir carnauba. Skandeer-elektronmikrograwe het 'n amorfe gekristalliseerde natuurlike wakslaag met onbedekte stomata op die oppervlak van onbedekte vrugte getoon. Die dikte van die toegediende waks het met toename in wakslading toegeneem. Wakslae na toediening met sintetiese borsels teen 1.2 L.ton-1 het dikker vertoon in vergelyking met perdehaar borsels. Hierdie studie het die effekte van borseltipe op die verspreiding en polering van die wakslaag op die oppervlak van vrugte getoon, en versigtige toediening van wakslae onderskryf, aangesien ónder- of óórtoediening swak resultate, in terme van bio-effektiwiteit, residu-lading en vrugkwaliteit, tot gevolg kan hê.
National Research Foundation, THRIP, Citrus Academy & Citrus Research International for bursary and research funding.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
In this study, the efficacy of coatings comprising gum arabic (GA) and the essential oil from Origanum vulgare L. (OVEO) alone or in combination and Rosmarinus officinalis L. (ROEO) as a postharvest treatment to control Rhizopus soft rot on plums during storage at room temperature (25 °C for 8 days) and cold temperature (12 °C for 21 days) was evaluated. The effects of these coatings on some physicochemical and sensory characteristics of the fruit were also assessed. The minimum inhibitory concentrations (MIC) of OVEO and ROEO were 0.25 μL/mL and 1 μL/mL, respectively. The Fractional Inhibitory Concentration Index of the combined EOs (≤ 0.25) against Rhizopus stolonifer indicated a synergic interaction. The incorporation of a combination of GA and OVEO at 0.25 μL/mL or of GA and OVEO at 0.06 μL/mL plus ROEO at 0.25 μL/mL in the growth media strongly inhibited the mycelial growth, spore germination and sporulation of R. stolonifer. Both the combination of GA + OVEO and GA + OVEO + ROEO delayed the occurrence of soft rot in artificially contaminated plums and decreased the number of infected fruits at the end of storage at room and cold temperatures. GA-OVEO or GA-OVEO-ROEO coatings preserved the postharvest physicochemical quality aspects and enhanced the sensory parameters color and flavor of plums. However, the GA-OVEO coating negatively affected the aftertaste of fruit. Fruit coated with GA-OVEO and GA-OVEO-ROEO exhibited greater amounts of xylose, malic and ellagic acid and rutin at the assessed storage period. These results indicate the coatings comprising GA and OVEO alone or in combination with ROEO as promising postharvest treatments to prevent the Rhizopus soft-rot and preserve the postharvest quality in plums.
Este estudo avaliou a eficácia de revestimentos de goma arábica (GA) e óleo essencial de Origanum vulgare L. (OEOV) sozinho ou em combinação com o óleo essencial de Rosmarinus officinalis L. (OERO) como tratamento pós-colheita para controlar a podridão mole causada pelo fungo Rhizopus stolonifer em ameixas durante o armazenamento à temperatura ambiente (25 °C durante 8 dias) e temperatura refrigerada (12 °C durante 21 dias). Os efeitos dos revestimentos nas características físico-químicas e organolépticas dos frutos também foram avaliados. As concentrações inibitórias mínimas (CIM) do OEOV e do OERO foram 0,25 μL/mL e 1 μL/ mL, respectivamente. O Índice de Concentração Inibitória Fracionada dos óleos essenciais (EOs) combinados foi ≤ 0,25 contra Rhizopus stolonifer indicando interação sinérgica. A incorporação da combinação de GA (1 mg/mL) e OEOV (0,25 μL / mL) ou de GA (1 mg/mL) e OEOV (0,06 μL / mL) + OERO (0,25 μL / mL) inibiu fortemente o crescimento micelial, a germinação de esporos e a esporulação de R. stolonifer. As combinações de GA + OEOV (GA-OEOV) e GA + OEOV + OERO (GA-OEOV-OERO) retardaram a ocorrência de podridão mole em ameixas artificialmente contaminadas e reduziram o número de frutos infectados no final do armazenamento na temperatura ambiente e refrigerada. Os revestimentos GA-OEOV ou GA-OEOV-OERO preservaram os aspectos de qualidade físico-químicas pós-colheita e reforçaram os parâmetros sensoriais cor e aroma das ameixas. No entanto, o revestimento GA-OEOV afetou negativamente o atributo sabor residual. Frutos revestidos com GA-OEOV e GA-OEOV-OERO exibiram maiores quantidades de xilose, ácido málico, elágico e rutina nos períodos de armazenamento avaliados em comparação com aqueles não-revestidos. Esses resultados indicam que revestimentos de GA e OEOV sozinho ou em combinação com OERO são tratamentos promissores para a prevenção da podridão mole e manutenção da qualidade pós-colheita de ameixas.

The subject of this thesis is to verify effect of aluminium powder in ground refractory coatin, which is intended for casting od steel castings to organic bonded moulds. The pre-sence of aluminium powder in ground coating was expertised on term of coating in itself - that means immunity to heat shock, penetration etc., and in term of influence on formation of surface defects etc. Outputs of this thesis are: setting of optimum amount of aluminium powder in ground coating and statistically verified analysis of effects of modified coating in term of creation of defects

Dissertação de Mestrado em Segurança Alimentar
O chouriço tradicional Português é bastante apreciado pelos consumidores sendo comercializado sob embalagens em atmosfera modificada ou a vácuo. Após aquisição deste produto, os consumidores abrem as embalagens e conservam-no em refrigeração. Na superfície do chouriço desenvolvem-se frequentemente bolores dando-lhe características organoléticas repugnantes que levam à sua rejeição. O objetivo deste trabalho consistiu em estudar o efeito de revestimentos ativos incorporados com péptidos antimicrobianos nisina (NS,1%) e/ou natamicina (NT,0,05% e 0,025%) para inibir o desenvolvimento dos bolores na superfície dos chouriços. Revestimentos de quitosano (Q,0,5%) e lactato de sódio (LS,2,4%) com antimicrobianos imobilizados foram testados em tripa seca natural, contaminada com Penicillium funiculosum: Q(0,5%)+LS(2,4%); Q(0,5%)+LS(2,4%)+NS(1%); Q(0,5%)+LS(2,4%)+NT(0,05% e 0,025%); Q(0,5%)+LS(2,4%)+NS(1%)+NT(0,05%). O revestimento Q(0,5%)+LS(2,4%)+NT(0,025%) revelou ser o mais promissor, inibindo o desenvolvimento do bolor até 60 dias. Este revestimento foi aplicado em chouriço tradicional, revelando-se eficaz no controlo do desenvolvimento de bolores na superfície do produto, até pelo menos 30dias de armazenamento em condições semelhantes às da casa do consumidor, não afetando contudo as bactérias do ácido láctico (LAB) e Staphylococcus coagulase negativos, microbiota tecnológica do produto, assim como a atividade da água (aw) e pH do enchido que contribuem para a sua estabilidade.
ABSTRACT - EFFECT OF ACTIVE COATINGS ON THE SHELF LIFE OF TRADITIONAL PORTUGUESE SAUSAGE - The traditional Portuguese sausage “chouriço" is very appreciated by consumers and is marketed under modified atmosphere packaging (MAP) or vacuum. After purchasing this product, consumers open the package and put it under refrigeration. On the surface of the sausage develops moulds giving them an unappealing aspect and rejection to consume. The aim of this work was to study the effect of active coatings incorporating antimicrobial peptides Nisin (NS, 1%) and/or Natamycin (NT, 0.05% and 0.025%) to inhibit the growth of moulds on the surface of fermented smoked sausages. Chitosan coatings (Ch,0,5%) and Sodium Lactate (SL,2.4%) with immobilized antimicrobial were tested on natural dried casings, contaminated with Penicillium funiculosum: Ch(0.5%)+SL(2.4%); Ch(0.5%)+LS(2.4%)+NS(1%); Ch(0.5%)+LS(2.4%)+NT(0.05% and 0.025%); Ch(0.5%)+SL(2.4%)+NS(1%)+NT (0.05%). The coating Ch(0.5%)+LS(2.4%)+NT(0.025%) was the most promising, inhibiting the development of mould up to 60 days. This coating was applied on traditional sausage chouriço, being effective to control the growth of moulds on product surface, up to at least 30 storage days in similar conditions to those held at consumer's home, without affecting lactic acid bacteria (LAB) and coagulase negative Staphylococcus, the technological microbiota of the product, as well the sausage water activity (aw) and pH which contributes to its stability.

碩士
國立臺灣海洋大學
機械與機電工程學系
99
This study is mainly to adopt different coating technical to improve the life cycle of die steel using on aluminum melt. There are three kinds of testing specimens of die steel, the un-coated testing specimen, Cr-N(Chrome-Nitrogen) coated with oxygenation testing specimen, and plasma spray welding of aluminum oxide testing specimen applying to the ADC12 aluminum melt for purpose of carrying out heat resistance of washout tests in static, and dynamic stirring condition. While completion of those tests, those testing specimens are needed to clean up and dry, and put on the precision scale for measuring the actual weight loss of each testing specimen in order to realize the heat resistance capabilities of melting weight loss test for each test specimen in static, and dynamic stirring condition. Finally, a microscope is used to obverse the microstructure of each testing specimen, and a NDT (Non-Destructive Testing) of x-ray is also used to each testing specimen for obtaining the reaction condition of melting weight loss as the die steel put into the ADC12 aluminum melt. As a result shows that there is only 0.3% melting weight loss at minimum for applying the plasma spray welding of aluminum oxide coating technology on the surface of die steel. Comparing this result with the other test results of 5.8% melting weight loss on un-coated testing specimen, it is found that the plasma spray welding of aluminum oxide coating technology has improved the 80% melting weight loss which is better than the un-coated one, and other coating technology is also presenting an effect to reduce the melting weight loss of steel stirrer in this study. Observation of the micro-structure of each testing specimen, we will figure out the corrosion way on the die steel is starting from the chemical diffusion reaction between Fe element of the die steel and ADC12 aluminum melt, which occurs the Fe-Al-Si compound, and this die steel is further being corroded by ADC12 aluminum-base melt. So, the plasma spray welding of aluminum oxide coating technology on the die steel specimen is mainly to form a protection film so that it can barrier the chemical diffusion reaction and the Fe-Al-Si compound layer between both materials of them for the purpose to reduce the rate of melting weight loss on die steel.

碩士
國立中興大學
材料工程學系所
96
The electrolytic deposition of alumina(Al2O3) coatings on post electrolytic zirconia(ZrO2) deposited STAVAX 420 mold tooling steel. The better condition of ZrO2/Al2O3 coated on specimens were determined by controlling different electrical-chemical parameter (concentration、potential、time) and different sintering conditions. The followed characterizations were conducted by using Potentiostat、SEM/EDS、XRD、hardness tests、wear tests、scratch test and dynamic polarization tests. Sweeps the cathode polarization curve because of the designation electrolyte consistency to the metal substrate, and discovers the best deposition electric potential and the time, matches the best annealing temperature again, may obtain the best deposition thin film and its characteristic. XRD diagrams indicate from this method prepares ZrO2/Al2O3 coated on specimens when 450℃ annealed is γ-Al2O3. The experimental result showed that thin film surface condition resistance corrosiveness has the enormous influence, when thickness is too thick, the thin film can have the crack appearance, the thin film phase transformations will also affect the corrosion resistance height. Knew by the experimental result that the ZrO2/Al2O3 coated on specimens in deposits 600 to 800s annealing temperature when 450℃ has the good corrosion resistance. The hardness tests indicated that the increasing annealing temperature enhanced the hardness increase in the coatings. The wear tests using polycarbonate (PC) as a pin, weight loss of the coated specimen was only 1/5 of the uncoated materials. The scratch tests indicated that the adhesion strength of the coating was greater than the yield stress of the metal substrate. In the vestige end part of alumina and zirconia still remains on the STAVAX 420 Mold Tooling Steel from SEM/EDS analysis. Cycle polarization tests in Hank’s solution indicate that the ZrO2/Al2O3 coating has a better quality in resistance corrosion than the STAVAX 420 Mold Tooling Steel. Electrochemical polarization tests of the coated specimen and SEM observation revealed 1/10 lower corrosion current than the uncoated in 1 M CH3COOH and 3.5% NaCl aqueous solutions. From all kinds of analysis to show that electrolytic deposition of ZrO2/Al2O3 ceramic thin film on STAVAX 420 Mold Tooling Steel have good corrosion resistivity.

碩士
國立交通大學
機械工程系所
103
Glass hot embossing is an important technique for optical elements fabrication in recent years. It is generally used to manufacture optical lenses with the advantages of low-cost and steady quality. In the molding process, glass is often sticking with mold and that will make mold damage and poor product yield. In generally some materials like Pt-Ir and DLC films can be coated on the mold surface or hardened alloys such as WC, SiC, GC can be used to make the mold to solve the sticking problems, but both solutions suffer from high cost and manufacture difficulties, also, from research on related litenatures, there are no evidence that show the relationship between glass sticking and the surface free energy of coated materials. Therefore, this research tries to use coating materials with lower cost for the non-sticking coating for glass hot embossing, and also expects to verify if the surface free energy method can be used to effectively determine the sticking behavior of the glass and films before the hot embossing process. In the beginning of this research, non-sticking coatings with CrN and SiN were successfully made. After that, the surface free energy of the films were calculated and both the glass contact and glass hot embossing experiments were conducted. Experimental results showed that, the lower surface free energy and the better the thermal stability of the films, the less sticking was found between the films and glass.

碩士
國立成功大學
材料科學及工程學系
87
The objective of this study is to measure the temperature distribution between the casting and the metallic mold during the casting process. The casting/mold interfacial heat transfer coefficient, h, is then computed by using the Inverse Method along with the measured temperature data. In this study, the interfacial heat transfer coefficient, h, is measured for A356 aluminum casting alloy in conjunction with two metallic molds(SKD-61 and FCD-500), two coating materials(DYCOTE 39 and AL-130), and three controlled coating thicknesses. A one-dimensional solidification heat transfer apparatus has been established and twelve heat transfer experiments for A356 aluminum alloy have been conducted. For DYCOTE 39 which is a heat insulating coating material to be sprayed on a SKD-61 mold surface, the peak values of h range from 0.02 ℃to 0.045 ℃near 575℃ and from 0.027 ℃ to 0.065 ℃ near eutectic temperature(545℃) for coating thickness between 43.5μm and 183.0μm. For AL-130 which is a chill coating material to be sprayed on the SKD-61 mold surface, the peak values of h range from 0.02 ℃to 0.045 ℃near 575℃ and from 0.05 ℃ to 0.16 ℃ near eutectic temperature(545℃) for coating thickness between 34.6μm and 169.3μm. For DYCOTE 39 sprayed on the FCD-500 mold surface, the peak values of h range from 0.02 ℃to 0.04 ℃near 575℃ and from 0.03 ℃ to 0.06 ℃near eutectic temperature for coating thickness between 51.7μm and 173.6μm. For AL-130 sprayed on the FCD-500 mold surface, the peak values of h range from 0.0175 ℃to 0.035 ℃near 575℃ and from 0.0275 ℃ to 0.04 ℃ near eutectic temperature for coating thickness between 40.2μm and 181.7μm. It is also found that regardless the kind of mold coating and thickness of the mold coating, the interfacial heat transfer coefficient dropps dramatically near 575℃and eutectic temperature(545℃). For the same coating, the value of h decreases as the thickness of coating increases.

碩士
國立成功大學
工程科學系碩博士班
101
Potting compound plays a crucial role in maintaining the stability of chip while packaging the electronic integrated circuit (IC). During the process of curing, the phenomenon of Epoxy Molding Compound (EMC) adhering to the surface of packaging molds is called adhesion effects. However, overreaction of the effect during mold releasing causes damages to the surface of IC products, including defective edge and uneven surface, which might result in the failure of packaging, low efficiency, and low reliability. Therefore, how to efficiently cut down the adhesion force between the surface of molds and specimen with special surface treatment, such as coating and heat treatment, has been emphasized and regarded as an important issue for academic research and industrial institutions. In the present study, automatic electronic packaging testing equipment and measuring technique made in our laboratory are used to examine the adhesion force. Previous studies failed to explore and measure the heat stability of the chips coating. Therefore, after coating the chips, this research aims to: 1. investigate surface oxide created in different coating and observe the effect before and after the Pre-Oxidation treatment; 2. compare stability of adhesion effect between two different kinds of coating, including T-series coating commonly used in industrial community and Ti-series coating commonly used for molds with high heat; and 3. observe and test the heat stability and adhesion effect of the Ni-series coating commonly used for the molding glass of optical lens to see the stability under the temperature of packaging. Finally, the adhesion effect experiments on speciemen’s pre-oxidation treatment for 400 shots are carried out to observe the changing trends of adhesion force. Through the anaysis of linear regression, the results of the characteristic curve of eah experiment are produced and compared to understand the different adhesion effect while packaging before and after pre-oxidation treatment and surface oxide created in different coating. Findings in the present study are expected to judge the best time for mold cleaning and to see whether these coatings can effeciently cut down the negative influences of adhesion effects or not.

碩士
國立成功大學
航空太空工程學系專班
95
Due to the improvement of injection molding technology, a lot of products become smaller and more delicate.The micro-injection molding gradually plays a major role in the mass production. This study utilized the surface rapid heating system to understand the heating effect on the micro-injection molding. A graphite thin film (0.1μm thickness) was coated onto the surface of insert the mold by ion sputtering to enhance the heat absorption during the infrared heating.Space the result shows that the injection process was enhanced by the graphite coating as well as the surface rapid heating system. In addition, the cavity temperature sensor indicates that the temperature of the mold is needed to be higher than the glass transition temperature to have a complete molding.

碩士
明道大學
材料科學與工程學系碩士班
98
Glass molding technology is considered to be the most likely candidate to successfully produce high resolution and stability aspherical glass lenses in vast volumes. This study reports upon the deposition of CrAlSiN/CrN, TiAlSiN/TiN and AlTiN/CrN multilayer nanofilms through the use of cathodic arc deposition. When using a tungsten carbide coated substrate mold, the mold modifies the surface of the glass. The high temperature wetting of a Sumita Optical Glass K-PG325 ball was studied by contact angle measurements. These measurements were used to explore the affect of operating temperature and film composition upon adhesion characteristics. X-ray diffraction analysis showed that all multilayer nanofilms possessed a FCC crystal structure. Nanoindentation results showed that, CrAlSiN/CrN film has the greatest hardness (36.8 ± 2GPa). Furthermore, heat treatment under a pressurized nitrogen environment at 700 °C resulted in a measured hardness value of 37.5 ± 1GPa, indicating that CrAlSiN/CrN films possess excellent resistance against thermal fatigue. CrAlSiN/CrN multilayer films demonstrate the best antioxidant capacity in high-temperature oxidation tests, with thermal stability up to 1000 °C. The unusually low contact angle measured at temperatures above 600 °C revealed a possible interfacial reaction between the glass mold and the coating, resulting in severe adhesion effects. At 700 °C the contact angle between the CrAlSiN/CrN film and the glass ball was found to be largest (80 °), this indicated that the chemical reactivity between the film and glass was much lower. This was mainly due to the antioxidant effect of the deposited film; an oxidation layer in the film can diffusively exchange with the oxides in the glass, thus resulting in adhesion. The results show that CrAlSiN/CrN films have excellent thermal fatigue resistance and resistance to high temperature oxidation, which makes them ideal as a protective coating for tungsten carbide-coated optical glass.

Tese de doutoramento em Engenharia Mecânica (Pré-Bolonha), Especialidade de Tecnologia da Produção, apresentada à Faculdade de Ciências e Tecnologia da Universidade de Coimbra
Coatings are frequently applied on molds and accessories for the glass industry in order to restrict surface degradation such as oxidation, corrosion, abrasion and wear of the structural material, thereby decreasing the maintenance costs and increasing the lifetime and performance of components. However, in order to obtain accurate lifetime expectancies and performance of the coatings it is necessary to have a complete reliable understanding of their properties. This thesis is on the improvement of the surface properties and integrity of molds, in order to increase their durability, through the application of different types of coatings. Two methodologies were followed to reach such demands: 1 - synthesis, optimization and characterization of coatings currently used in molds surface protection (Ni-based alloys deposited by Plasma Transferred Arc); 2 - synthesis and characterization of new coatings with improved functionalities, deposited by emergent deposition processes such as Atmospheric Plasma Spraying and DC Reactive Magnetron Sputtering. In a first step it was intended to optimize Ni-based coatings deposited by PTA process, studying the effect of substrate dilution on the properties of coatings. In the second part, two different coating systems were evaluated. The first topic investigated the effect of ZrO2 additions on the microstructure, mechanical properties and tribological behavior to Ni-based alloy coatings deposited by APS process, whilst, in the second the influence of V additions on the properties of TiSi(V)N thin films, containing different Si and V contents, deposited by DC reactive magnetron sputtering, was evaluated. The main results to be enhanced are described below for each coating system investigated. The dilution of the substrate showed strongly influence the structure and consequently the hardness, oxidation resistance and tribological behavior of coatings. It was observed that increasing dilution had a detrimental effect on the hardness, oxidation resistance and tribological behavior of coatings at room temperature due to base material incorporation. However, in the latter it demonstrated to have a beneficial effect at high temperature due to the fast formation of oxide layers which protect the coating surface against wear. The post-weld heat treatment performed at coatings reduced the hardness of the partially melted and heat affected zones without affecting the coatings hardness. Furthermore, coatings hardness and wear resistance was increased with annealing treatment. Thus, the best performing coating could only be achieved by, selecting the proper deposition conditions that give the best correlation among mechanical properties, level of oxidation and wear resistance of coatings. ZrO2 additions promoted different impact on the microstructure of a Ni-based alloy, when coatings were deposited using powders mixed by mechanical alloying or using separated powders. A homogeneous and compact microstructure with small zirconia particles evenly distributed in the matrix was obtained in the first case, while a porous microstructure, full of semi-melted Ni powders with large particles of ZrO2 entrapped in their boundaries suggesting a brittle behavior was obtained in the second. In both cases the hardness and wear behavior of ZrO2 rich coatings in relation to the Ni-based one, was improved. However, coatings deposited by powders prepared my mechanical alloying revealed to be much more performing due to their compact structure and even distribution of zirconia. All the APS coatings showed higher hardness values than the Ni-based coatings deposited by PTA, however, their micro-abrasion resistance revealed to be worst, due to the lack of cohesion between powders. The structure of V rich coatings analysed by XRD revealed that V incorporations to the TiSiN system shift the peaks to higher angles, indicating a substitutional solid solution due to the substitution of Ti by smaller V atoms. On the other hand, X-ray diffraction analyses performed at the TiSiN films revealed that the stoichiometric nanocomposite structure for the control of vanadium diffusion was not formed. In fact Si incorporation at the TiN system revealed to shift the diffraction peaks to higher angles, which in combination to the same level of compressive residual stresses measured for all the Si rich films, indicted substitutional solid solution formation. V additions showed successfully increase the hardness and tribological behavior of TiSiVN films. The hardness improvement with V incorporations has shown to be a result of the substitutional solid solution formation, whilst, the improvement of the tribological properties is related to the V2O5 phase formation on the sliding contact that acts as a lubricious tribo-film, which protects the coating from wear. The oxidation resistance of Si and V rich coatings showed to be strongly influenced by their structure. Si and V incorporations at the TiN and TiSiN systems, showed improve and abruptly decrease the oxidation resistance of films, respectively. The oxidation resistance decrease of V rich coatings was attributed to the rapid V ions diffusion throughout the oxide scale, which inhibited the formation of a continuous protective silicon oxide layer, as opposed to TiSiN films case, where a continuous and protective SiO2 layer was built leading to a much lower oxidation weight gain over time. V rich coatings showed lower oxidation resistance than Ni-based coatings PTA, but superior hardness values (some orders of magnitude higher) and greater tribological behavior than PTA and APS deposited coatings.
Diferentes tipos de revestimentos são frequentemente aplicados em moldes e acessórios para a indústria do vidro, de forma a atenuar a degradação das suas superfícies, devida às extremas condições de oxidação, corrosão, abrasão e desgaste de uso a que estão sujeitos, diminuindo desta forma os custos de manutenção e aumentando o tempo de vida e o desempenho destes componentes. No entanto, de forma a maximizar o desempenho dos revestimentos, é necessário ter uma completa e fiável compreensão das suas propriedades. Esta tese é totalmente dedicada à melhoria das propriedades da superfície dos moldes, de forma a aumentar a sua durabilidade e performance, através da aplicação de diferentes tipos de revestimentos. No sentido de dar cumprimento a este desafio, duas metodologias foram seguidas: 1 - síntese, optimização e caracterização de revestimentos actualmente usados na protecção da superfície dos moldes (ligas à base de Ni depositadas por PTA (plasma transferred arc)); 2 - síntese e caracterização de novos revestimentos mais resistente e com melhores propriedades, depositados por processos de deposição emergentes no mercado, tal como são os casos do APS (atmospheric plasma spraying) e do PVD (physical vapor deposition). Primeiramente estudou-se o efeito da diluição do material base nas propriedades de uma liga de níquel depositada por PTA usada actualmente na protecção da superfície dos moldes. Na segunda parte diferentes sistemas de revestimento foram avaliados. O primeiro estudo incidiu sobre o efeito da adição de ZrO2 nas propriedades mecânicas, microestrutura e comportamento tribológico de uma liga de Ni depositada por APS, enquanto que o segundo estudo recaiu na análise da influência da adição de V nas propriedades de revestimentos cerâmicos de TiSiN, contendo diferentes teores de Si e V, depositados por PVD. Os principais resultados alcançados durante este trabalho são resumidos seguidamente, para cada um dos sistemas de revestimentos analisados. A diluição do substrato mostrou influenciar a estrutura e consequentemente diminuir a dureza, resistência à oxidação e resistência ao desgaste à temperatura ambiente dos revestimentos. No entanto, teve um efeito benéfico no comportamento tribológico a temperaturas elevadas, devido à rápida formação de uma camada de óxido, que mostrou proteger a superfície contra o desgaste. O tratamento térmico efectuado aos revestimentos após deposição reduziu com sucesso a dureza das zonas termicamente afectada pelo calor e parcialmente fundida, sem alterar a dureza da zona fundida. Além disso, o tratamento de envelhecimento realizado aos revestimentos mostrou aumentar a sua dureza e a sua resistência ao desgaste com a exposição à temperatura. Assim, o revestimento com melhor desempenho só pode ser obtido seleccionando as condições de deposição que originem o melhor compromisso entre propriedades mecânicas, nível de oxidação e de resistência ao desgaste. A adição de zircónia à liga de níquel depositada por APS, usando pós de Ni e ZrO2 misturados por síntese mecânica e pós separados promoveu diferente impacto na microestrutura dos revestimentos. Quando depositados com pós preparados por síntese mecânica, os revestimentos exibiram uma estrutura homogénea e compacta com pequenas partículas de zircónica uniformemente distribuídas al longo da matriz de Ni. Por outro lado, quando depositados separadamente obteve-se uma estrutura extremamente porosa com pós de Ni semi-fundidos e com partículas de ZrO2 aprisionadas na sua interface, sugerindo um comportamento frágil. Independente do procedimento de deposição usado, em ambos os casos a dureza e a resistência ao desgaste dos revestimentos foi melhorada com a adição de ZrO2. Contudo, os revestimentos depositados usando pós produzidos por síntese mecânica revelaram possuir uma maior performance, devido à sua estrutura compacta e distribuição uniforme de ZrO2. Todos os revestimentos depositados por APS revelaram possuir valores de dureza superiores aos revestimentos depositados por PTA, no entanto, a sua resistência à abrasão mostrou ser bastante inferior devido à falta de coesão entre pós. As análises de difracção de raio-X realizadas aos filmes ricos em V revelaram que os picos de difracção se deslocam para ângulos superiores com o aumento do teor em V, indicando a formação de uma solução sólida substitucional. Por outro lado, a análise realizada aos revestimentos de TiSIN revelou que a estrutura estequiométrica nanocompósita, requerida para o controlo da difusão de vanádio não foi formada. De facto, a adição de Si ao sistema TiN revelou também deslocar os picos de difracção para ângulos superiores, o que em combinação com o mesmo nível de tensões residuais medido nos diferentes revestimentos, indica a formação de uma solução sólida substitucional. A Adição de V ao sistema TiSiN mostrou aumentar com sucesso as suas propriedades mecânicas e tribológicas. O aumento da dureza com a adição de vanádio foi atribuído à formação da solução sólida substitucional, enquanto, a melhoria das propriedades tribológicas está relacionada com a formação da fase V2O5, no topo da superfície do filme, a qual age como lubrificante sólido, e portanto protege o revestimento de desgaste. A resistência à oxidação de revestimentos ricos em Si e V mostrou ser fortemente influenciada pela sua estrutura. A adição de Si e V aos sistemas TiN e TiSiN, respectivamente, mostrou aumentar e abruptamente reduzir a resistência à oxidação dos filmes. A diminuição da resistência a oxidação dos revestimentos ricos em V foi atribuída à rápida difusão dos iões de V através da camada de óxido, o que inibiu a formação de uma camada contínua e protectora de óxido de silício, contrariamente ao que acontece nos revestimentos TiSiN, onde uma camada contínua e protectora de Si-O foi formada, levando a menores taxas de ganho de massa devido à oxidação com o tempo. Os filmes ricos em V apresentaram menor resistência à oxidação do que os revestimentos espessos depositados por PTA, no entanto, a sua dureza e resistência ao desgaste mostrou ser bastante superior aos dos revestimentos depositados por PTA e APS.

碩士
南台科技大學
奈米科技研究所
98
This study presents the fabrication of soft roller mold by using a jet-based spin coating system and transferring the pattern from a metal roller mold with 3D microstructures array. The novel roller coating system consists of three parts: a desktop lathe, polymer supply system and air jet system. And, the coating process was implemented by following procedure; a viscous polymer was firstly dripped and spun by a syringe pump and the lathe rotation. Then, a high-pressure air jet was sprayed on the coated roller to flatten and thin the polymer layer by using a flat-shape nozzle, at last, the thin polymer film on the roller was cured by a infrared-ray heater attached on the coating system. In the experimental results, the thickness of PDMS thin film on the roller can be controlled from15μm to 100μm with ±3μm uniformity by adjusting the air pressure and the gap between nozzle and roller. Based on this roller coating technology, we developed three approaches for fabrication of PMDS soft roller mold. First method is molding by a flexible substrate with microlens array after the roller has been coated with uncured PDMS. The second method is coating PDMS film on a roller covered on a flexible substrate with microlens array so that the opposite microstructure can be transferred to a PDMS film, then a soft roller mold can be made after the PDMS film is wrapped on the roller. The third method is first coating PDMS film on a roller mold with microstructures array and then second coating the patterned PDMS film on a roller. The final microstructure on the second-coated PDMS film is the same with the original roller mold. Therefore, a soft roller mold can be fabricated by wrapping up the second-coated PDMS film. Generally, the third method is potentially to fabricate a seamless soft roller mold; in addition, the uncertainty of process also can be reduced for the mass production. Basically, the PDMS soft roller mold not only solves the sticking problem on metal roller mold in the UV-curing roll-to-roll process but also reduces the damage of high-cost metal roller mold.

碩士
國立臺灣科技大學
機械工程系
98
This thesis is aiming the Electroless Ni-P/PTFE composite coating on high thermal plastic mold, this kind of mould surface deals with very extensive application of plastic mold, such as car installs, electronic products etc. This is thesis studies of wear-resisting and corrosion-resistant behavior on Ni-P/PTFE composite coating, Set constant load strength for wear performance on specimens utilizing Cameron-Plint, TE-77 reciprocating friction machine, and record test data for friction after wear of un-coating and coating specimens. And observe worn surface utilizing Scanning Electronic Microscope. Redo wear performance on specimens after SO2 gas corrosion test. Record test data for friction after wear and observe worn surface on un-coating and coating specimens. The result and actually application are show, the Electroless Ni-P/PTFE composite coating mold is better than un-coating mold , Because of the coating mold is get good performance of wear-resisting and corrosion-resistant, and easy to draw pattern and get good product surface for high thermal plastic mold when process a injection. The result is for reference of develop precision mold in the future.

Thesis (M.S.)--Florida State University, 2004.
Advisor: Dr. Okenwa Okoli, Florida State University, College of Engineering, Dept. of Industrial Engineering. Title and description from dissertation home page (viewed Oct. 27, 2004). Includes bibliographical references.

碩士
國立中興大學
材料工程學研究所
88
The electrolytic deposition of alumina(Al2O3) coatings on post electrolytic Ni deposited SKD61 was conducted in an aqueous solution of alumina-nitrate[Al(NO3)3]. The better condition of alumina coatings on Ni alloy was determined by controlling different electrical-chemical parameter (solvent 、concentration、potential、time) and different sintering conditions. The followed characterizations were conducted by using Potentiostat、SEM/EDS、XRD、wear test and scratch test. From the left shifting of the polarization curves, it was known that the diffusing of Al+3 ions in solvent is decreased with decreasing water content in electrolyte. A thicker alumina-film without cracks can be deposited in the electrolyte containing less water. XRD diagrams indicate that the phase transformations of alumina are (1) for alumina-powder (2) for alumina-film The above difference between alumina-powder and alumina-film is controlled by the water-contained amount of alumina-hydrate. Through the cycle polarization test in 3.5%NaCl, it was found that the corrosion potential、corrosion current and protection potential of both Al2O3 deposited specimens are better than Ni alloy and substrate, except ta deposited specimen which showed a lower protection potential due to the cleavage of Al2O3 films after pitting. The wear tests with a load of 24.5N show that the wear loss of alumina-films by Al alloy pin is lower than both that of Ni and SKD61. The least one is only 1/28 of SKD61 substrates. SEM/EDS observations and the scratch tests, revealed that Ni layer was first detached from SKD61 under shear stress of 2.23GPa. This also means that the adhesion between Al2O3 and Ni is better than that between Ni and SKD61.

碩士
國立臺灣科技大學
機械工程系
104
The mould coatings is a layer of refractory applied on the surfaces of expandable polystyrene patterns or casting sand mould, to separate the casting metal liquid from contacting mould, its properties will affect the quality of castings. Ability for air or gases to pass through is one of the most important properties of the coatings, which directly related to the characteristic of refractory. In this research an experimental set-up was used employing Darcy’s law to measure the permeability of mould coatings, to investigate the effects of granular shapes, sizes, particle distribution of refractory, and additives flake graphite or fibrous calcium silicate on the permeability. The results shows that coatings made of a larger size of ceramic sand has a higher permeability, however the effect of additives depends on the particle shape and its relative amount. The coatings after calcinations in a furnace with a temperature ranged between 780~810 ℃for 3 minutes shows a higher permeability. The micro topographies from SEM shows that the particle sizes, shapes and relatives amount of additives will affect the void size existed in the coatings. Based on this observation, a model for the permeating mechanism associated with additives has been proposed.

A composite part manufacturing mold was considered one of the most important factors that affected a successful composite part manufacturing process for this research. A highly durable surface was required for the mold to prevent surface damages and increase mold life. A high surface finish quality of the mold improved the surface quality of the composite part and lowered the demolding force. However, the surface of additively manufactured fiber reinforced composite molds usually had lower durability and surface finish quality compared to traditional metal molds. To solve these issues, the author applied an additional coating on top of the additively manufactured fiber reinforced composite mold surface. A thermal analysis of the additively manufactured fiber reinforced composite material and the coating material were performed to select an applicable coating technique and coating material. The thermoset polymer coating with ceramic particles that was applied with a liquid spray coating technique was selected as a coating material. Various surface property tests were performed to evaluate the coated surface compared to the non-coated surface. The additively manufactured fiber reinforced composite test specimen manufacturing process and the coating application process were demonstrated in this study. The surface durability of the test specimens was tested using a surface hardness test and an abrasion resistance test. The surface performance of the test specimens was measured using a surface roughness test and a demolding test. The sustainability of the coating material on the additively manufactured fiber reinforced composite was tested using coefficient of thermal expansion (CTE) test, coating adhesion test, and mold life experiment. In the mold life experiment, the non-coated and coated mold were used for multiple composite part manufacturing processes to investigate how the coating affected the life of the mold. The test results showed that the coated surface had a significantly improved surface abrasion resistance and demolding performance. However, the coating did not significantly improved surface hardness and roughness with the coating. The adhesion strength of the coating was not degraded even there was a coefficient of thermal expansion (CTE) mismatch between the additively manufactured fiber reinforced composite and the coating material. The coated additively manufactured fiber reinforced composite mold was able to be used for multiple autoclave composite part manufacturing cycles. The coating covered most of the small voids on the mold surface and provided a more homogeneous surface compared to the non-coated mold, but the voids which could not be covered with the coating caused a chipped coating issue. Once the chipped coating occurred, the size of chipped coating got larger each time the tool was used for a composite part manufacturing cycle. Although the additional coating provided some improvements for the surface properties, the coating applied in this research could not be an ultimate solution to meet all the surface property requirements for composite part manufacturing mold.

Dissertação de Mestrado Integrado em Engenharia Mecânica apresentada à Faculdade de Ciências e Tecnologia
No contexto industrial da empresa Ansell Portugal, produtora de luvas para diversas aplicações, há um problema relacionado com a degradação precoce dos moldes metálicos, revestidos com PTFE, e que são utilizados como base de suporte das luvas não modificadas, designadas por liners, durante os procedimentos sofridos ao longo da linha de produção LP7. O objetivo inicial da presente dissertação é o de estudar a possibilidade de efetuar a substituição do atual molde metálico por um molde feito apenas em material polimérico. Neste contexto, o estudo foi iniciado pela caracterização do molde metálico, com e sem revestimento, de modo a ter uma base de informação que permita efetuar a escolha fundamentada de um possível material substituto. A caracterização efetuada permitiu observar que a razão que induz a rápida degradação dos moldes é a corrosão do molde metálico, cujos produtos se acumulam na interface substrato/revestimento. Este fenómeno eletroquímico, que deveria ser evitado pela presença do revestimento de PTFE, tem como origem a passagem dos moldes pelos tanques com solução ácida e salina, sendo depois catalisada pela temperatura a que os moldes estão sujeitos nas etapas de passagem pelos fornos. O revestimento de PTFE não cumpre a sua função devido ao facto de não cobrir uniformemente o substrato metálico, deixando o substrato diretamente exposto aos ambientes químicos agressivos. A caracterização efetuada demonstrou que, provavelmente, a melhor solução não será a substituição do tipo de molde utilizado, mas sim garantir que o revestimento cumpra a sua função. Tal poderá ser conseguido pela mudança do tipo de tecnologia utilizada para efetuar o revestimento ou por um controlo de qualidade mais eficiente. Apesar do estudo efetuado apontar para o facto de, no âmbito industrial da empresa, não haver uma necessidade premente na substituição do molde metálico foi ainda assim efetuado estudo de algumas propriedades de polímeros capazes de serem considerados como substitutos do molde metálico. Não tendo em consideração o fator económico os materiais selecionados foram o politetrafluoroetileno (PTFE), e os materiais compósitos de matriz poli(éter éter cetona) (PEEK) reforçado com 30% de fibras de vibro (FEEK FV30) e com 30% de fibras de carbono (PEEK FC30).
In the Ansell Portugal industry, a manufacturer of gloves for various applications, there is a problem related to the early degradation of PTFE coated metal moulds, which are used as a support base for liners during the LP7 production line. The initial objective of this dissertation is to study the possibility of replacing the current metallic material of the mould with a polymeric or a polymeric based material. Within this frame, the study was initiated by the characterization of the metallic mould, with and without coating, in order to have information that allows to make an informed choice of a possible substitute material. The characterization made it possible to observe that the reason that induces the rapid degradation of the moulds is the corrosion of the metallic material, whose products accumulate at the substrate / coating interface. This electrochemical phenomenon, which should be avoided by the presence of the PTFE coating, originates due to the passage of the moulds through the tanks with acidic and saline solution, and is then catalysed by the temperature at which the moulds are subjected in the furnaces. PTFE coating does not fulfil its function because it does not evenly cover the metal substrate, leaving it directly exposed to harsh chemical environments.The characterization carried out showed that the best solution is probably not to replace the material used for the mould, but to ensure that the coating fulfils its function. This can be achieved by changing the type of technology used to coat the metallic material or by a more efficient quality control of the dipping process. Although the study carried out pointed out that, in the industrial scope of the company, there was no pressing need to replace the metallic mould, it was still carried out a study of some properties of polymers capable of being considered as substitutes. The materials selected were polytetrafluoroethylene (PTFE), poly (ether ether ketone) (PEEK) composite reinforced with 30% glass fibres (FEEK FV30) and 30% of carbon fibres (PEEK FC30).

博士
中原大學
機械工程研究所
93
The purpose of this research is to establish mold surface temperature control using coating method and aims to achieve high mold surface temperature at filling stage so that plastics product quality can be improved without increasing cycle time. Influence of different coating materials and thickness on the contact temperature at mold surface and melt flow were analyzed first and the relevant mold design for experimental verification was also designed. Then efficiency of infrared heating combined with mold surface coating was also investigated. Finally, the improvements of tensile strength, weld line mark and residual stress in molded parts due to the present mold surface temperature control were also evaluated. In summary, heat hyesteresis via mold surface coating using PFTE and TiN provides efficient temperature controlling during melt-filling stage. When melt temperature for ABS is 240℃and mold temperature is 60℃, the contact temperature is 140.5℃for PTFE coating and 83.5℃ for TiN coating whereas for P20 without coating the contact temperature is only 71℃. Integrated with infrared heating, it take 17 second to increase mold surface temperature from 50℃ to 120℃. For PTFE coating with 22 μm and 10 μm thickness, the tensile strength improvement are 23.8% and 19.7%, respectively. For 4 μm TiN coating, the tensile strength increases by 23.8%. The experiment results also show the same tendency on and residual stress reduction and part cosmetic appearance. In summary, the results show that the mold surface coating provides an effective mold surface temperature control and also improves part qualities significantly.

Wax-based edible coatings for strawberry fruit were formulated and optimized. The weight loss was the preliminary quality parameter for determining the appropriate composition of the waxbased coating. Different combinations of wax to coconut oil ratio and amount of ethanol were performed to create a coating solution that would result in reduction of the weight loss while giving a desirable appearance. After conducting the preliminary study, it was concluded that the combination of 4 wax: 1 coconut oil in 70 mL ethanol was the best combination in order to significantly reduce the weight loss. Beewax and candelilla wax were used as the wax-basis, with coconut oil in the ratio 4:1. Both types of coating were applied onto strawberry fruits and these were evaluated for weight loss, surface color, ascorbic acid content, decay incidence, yeasts and mold count. A sensory evaluation was also performed. Strawberries were stored for 10 days at 10ºC. Both wax-based coatings produced significant reduction in weight loss in comparison to the uncoated fruits. Furthermore, a significant decrease of 20% and 15% in the reduction of ascorbic acid was noted on the 7th day of storage, for beewax - coconut oil coating and candelilla wax - coconut oil coating, respectively. The presence of mycelial growth often dictates the shelf-life of the strawberry fruit. In this study, a significant reduction in the decay incidence was observed both in beewax-coconut oil and candelilla wax-coconut oil coating. This was further supported by the lower yeast and mold count obtained for the coatings used. The changes in color between coated and uncoated fruits were not significantly different except for the L*value with higher values for coated fruits. In the sensory evaluation of the uncoated and coated fruits, judges also distinguished the color between the control and the treated fruits, after two days of storage at 4ºC. Significant differences were also noticed between fruits coated with candelilla wax- coconut oil and the control, regarding other sensory parameters. However, there were not significant differences between beewax-coconut oil based coating and the uncoated fruits. Edible wax-based coating of beewax-coconut oil and candelilla wax-coconut oil could help to extend the shelf life of strawberry since after 10 days of storage the yeasts and molds count was 4.0 × 105 cfu/g and 5.3 × 105 cfu/g for beewax-based and candelilla wax-based coated samples, respectively, lower than 9.4 × 107 cfu/g for the uncoated ones. However, those counts are still high, indicating a shelf life of beewax-based and candelilla wax-based coated strawberries shorter than 10 days.

碩士
淡江大學
機械與機電工程學系碩士班
98
Glass molding process（GMP）is considered to have great potential for mass production of spherical/aspheric glass lenses to a higher achievable accuracy and at a lower cost. However, GMP has its own problems to deal with such as sticking, oxidation, and diffusion at high temperature working environment. As a result, making mold life longer has become very critical in the GMP industry. This research aimed to investigate the interfacial chemical reaction between various optical glasses, different anti-stick coating designs and WC mold material. The results showed that, when its Co concentration got higher, WC mold had higher tendency to react with glasses. Efforts had been made in this study to investigate the effects of various protective coating designs. It was found that a Pt/Ir-compound coating on the mold could effectively suppress the interaction between the WC mold and optical glasses.