Dissertations / Theses on the topic 'Chromate resistance'

Nanometer thick layers of clay and polymer were formed on mica, silicon, and aluminum 2024-T3 alloy using alternating solutions of positively and negatively charged polymer and clay, respectively. Atomic force microscopy was used to observe the morphology of the composite films on mica and silicon. It was found that solution concentrations of clay above 0.02 weight percent lead to the uncontrolled deposition of clay platelets on the substrateâ s surface. By using solution concentrations of clay above 0.02 weight percent and ultrasonic agitation together it is possible to deposit a uniform monolayer of clay platelets on a mica substrate in £ 20 seconds. Ultrasonic agitation also produced crude patterns of montmorillonite platelets. Thin films of poly(diallydimethylammonium chloride) (PDDA) were made using concentrations ³ 2 weight percent of PDDA. It was found that the PDDA formed several unusual morphologies. Spherulites of PDDA were observed with AFM and the glass transition temperature of high molecular weight PDDA was measured using differential scanning calorimetry (DSC). Circular regions of positive charge were discovered on silicon wafers provided by three different sources. These areas of charge have never been reported in literature, but can easily be detected by placing wafers into solutions containing negatively or positively charged solutions of clay or polymer, respectively. The exact nature of these charged regions is unknown, but it is hypothesized that impurities on silicon wafers create the circular regions of positive charge. ISAM films made of a polyamide salt and a synthetic clay, Laponite RD®, demonstrated significant corrosion resistance on 2024-T3 Al alloys after 168 hours of salt spray testing. The ISAM films offered corrosion protection only if there was a significant layer of underlying surface oxide present, however. It was found that ISAM deposited films of polyarylic acid (PAA) and polyallylamine hydrochloride (PAH) may offer some corrosion resistance on 2024-T3 Al alloys, but these filmsâ corrosion resistance is severely hampered by the presence of Cl- in the PAH solution. Funding from this project was gratefully received from the Materials Science and Engineering Department at Virginia Tech; Luna Innovations Inc; the American Chemical Society / Petroleum Research Fund #34412-G5 and the Environmental Protection Agency Contract #68-D-00-244.
Master of Science

Diploma thesis deals with the technology of surface modifications of magnesium alloys. Basic knowledge from the field of the corrosion of metal materials. The division corrosion according to way of attack and corrosion environment, etc. There is an enumeration of ways of the corrosion defence. Questions of surface modifications with an emphasis on passivation by conversion coating and its analysis. Characteristics of magnesium and its alloys. Magnesium alloys with lithium, possibilities of its passivation and the verification of corrosion resistance. Enumeration of the used devices, chemicals and materials. characteristics of the used alloys. creation of the corrosion resistance standard. Research in passivation on the alloy containing 12 percent of lithium. The verification of the corrosion test usability based on the suggestion of the background research results. The test results for passivated as well as untreated samples and the reference material (steel). Aplication of chromate-free passivation and corrosion test on the alloy containing 12 percent of lithium.

BACKGROUND:Chromium is a toxic heavy metal, which primarily exists in two inorganic forms, Cr(VI) and Cr(III). Chromate Cr(VI)] is carcinogenic, mutational, and teratogenic due to its strong oxidizing nature. Biotransformation of Cr(VI) to less-toxic Cr(III) by chromate-resistant and reducing bacteria has offered an ecological and economical option for chromate detoxification and bioremediation. However, knowledge of the genetic determinants for chromate resistance and reduction has been limited so far. Our main aim was to investigate chromate resistance and reduction by Bacillus cereus SJ1, and to further study the underlying mechanisms at the molecular level using the obtained genome sequence.RESULTS:Bacillus cereus SJ1 isolated from chromium-contaminated wastewater of a metal electroplating factory displayed high Cr(VI) resistance with a minimal inhibitory concentration (MIC) of 30 mM when induced with Cr(VI). A complete bacterial reduction of 1 mM Cr(VI) was achieved within 57 h. By genome sequence analysis, a putative chromate transport operon, chrIA1, and two additional chrA genes encoding putative chromate transporters that likely confer chromate resistance were identified. Furthermore, we also found an azoreductase gene azoR and four nitroreductase genes nitR possibly involved in chromate reduction. Using reverse transcription PCR (RT-PCR) technology, it was shown that expression of adjacent genes chrA1 and chrI was induced in response to Cr(VI) but expression of the other two chromate transporter genes chrA2 and chrA3 was constitutive. In contrast, chromate reduction was constitutive in both phenotypic and gene expression analyses. The presence of a resolvase gene upstream of chrIA1, an arsenic resistance operon and a gene encoding Tn7-like transposition proteins ABBCCCD downstream of chrIA1 in B. cereus SJ1 implied the possibility of recent horizontal gene transfer.CONCLUSION:Our results indicate that expression of the chromate transporter gene chrA1 was inducible by Cr(VI) and most likely regulated by the putative transcriptional regulator ChrI. The bacterial Cr(VI)-resistant level was also inducible. The presence of an adjacent arsenic resistance gene cluster nearby the chrIA1 suggested that strong selective pressure by chromium and arsenic could cause bacterial horizontal gene transfer. Such events may favor the survival and increase the resistance level of B. cereus SJ1.

Melanoma is the most aggressive form of skin cancer with rapidly increasing rates of incidence in fair-skinned populations worldwide. The most promising current treatment for advanced stage melanoma involves a combination of chemotherapy and interferon alpha (IFN-α), although complete response rates are unacceptably low. Loss of sensitivity to IFNs in melanoma cells has been shown to arise from a deficiency in the level of intracellular signalling molecules including STAT1, STAT2 & IRF9, which are important transcription factors in the IFN signalling pathway. Of these, deficiencies in STAT1 show the greatest correlation with IFN resistance. Greater understanding of the regulation of STAT1 gene transcription is important for predicting, and potentially improving, IFN mediated activity in malignant melanomas. In a previous study, distinct enhancer and repressor regions were shown to be present in the first and second introns of the human STAT1 gene. A gene segment comprising 123 base pairs located in the second intron was shown to confer specific repression of reporter gene constructs in melanoma cell lines. Within this regulatory region, we have identified a putative repressor element-1 (RE1) site, and shown binding of the RE1 silencer of transcription (REST) protein in melanoma cell lines by chromatin immunoprecipitation (ChIP) assays. In transient transfection assays, a luciferase gene reporter construct comprising the RE1 sequence from the STAT1 gene cloned immediately downstream of the STAT1 promoter and enhancer regions exhibited significant repression of reporter gene activity. Furthermore, progressively stronger repression was conferred by cloning tandem copies of the STAT1-RE1 sequence adjacent to the promoter/enhancer region, confirming the repressive activity of this element. The partial loss of repression of the STAT1 promoter by the RE1 element in a cell line expressing a low level of the REST protein further confirmed the functional significance of REST and the RE1 element within the STAT1 gene.
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Medical Science
Griffith Health
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The methyltranferases Suv39h1 and Suv39h2 place the trimethyl mark on lysine 9 of histone H3 (H3K9me3). Heterochromatin Protein 1 (HP1) interacts with H3K9 through its chromodomain (Nielsen et al., 2001). Kap-1, another heterochromatin associated protein interacts with HP1, and together they help to form the compact heterochromatin structure. Without these methyltransferases, cells have less heterochromatin and increased genomic instability (Peters et al., 2001). Previous work in our lab (unpublished) showed that cells lacking these enzymes were more sensitive to ionizing radiation than wild type cells. This indicated a defect in double strand break repair. We wanted to ask if these cells were also more sensitive to methylating agents that cause damage that is repaired through the BER pathway. We found that cells lacking the Suv39h2 methyltransferase treated with MMS, a methylating agent, were more resistant to methylation damage than the wild type. We also wanted to ask whether Kap-1, a heterochromatin associated protein that interacts with the Suv39h1/2 methyltransferases, was phosphorylated after MMS treatment. We found ATM dependent phosphorylation of Kap-1, indicating that cells had relaxed chromatin after treatment with MMS. We hypothesize that this relaxation of chromatin gives the cells resistance to MMS as it allows for easier repair without the need for chromatin remodeling.

Les premières fibres optiques, développées dans les années 70, étaient multimodes. Le profil d’indice de type « saut d’indice » originel a rapidement cédé la place aux profils « à gradient d’indice », présentant une bande passante plus large. Malgré une bande passante plus faible, dû à la dispersion modale, les fibres multimodes (MMFs) ont su rester compétitives face aux fibres monomodes sur des applications utilisant des sources à grande ouverture numérique : grâce à leurs large cœur et grande ouverture numérique, elles sont plus tolérantes au désalignement source-fibre et fibre-fibre. Cette thèse entre dans le cadre du développement des MMFs pour les télécommunications, dans les réseaux locaux et les centres de données. Les sources optiques à base de diode laser à cavité verticale émettant par la surface disponibles depuis le début des années 2000 ont fait entrer les MMFs dans l’ère du multi-gigabit par seconde. Cette technologie a abouti à la standardisation des fibres OM3 en 2002 suivies des fibres OM4 (à la bande-passante modale plus de 2 fois plus large) en 2009, dont la bande passante modale est maximisée à 850nm. Ce travail présente les développements des fibres multimodes OM3 et OM4 de ces dix dernières années. Il se décompose en trois axes : i) l’optimisation de profil d’indice pour augmenter la bande passante modale des MMFs (développement des fibres OM4), ii) la minimisation des pertes par courbures des fibres OM3 et OM4 (développement de fibres OM4 résistantes à la courbure),iii) l’étude de la compensation de la dispersion chromatique dans les MMFs utilisées avec des VCSEL multimodes transverses, qui ouvre la voie à de nouvelles possibilités d’optimisation
Multi-Mode Fibers (MMFs) were the first optical fibers to be developed in the early days of optical communications, before the advent of Single-Mode Fibers (SMFs). Graded-Index MMFs (GI-MMFs) were rapidly introduced to reduce the modal dispersion, and thus enlarge the modal bandwidth, that limited the capacity of original Step-Index fibers (SI-MMFs), paving the way to short-range high-speed optical transmissions. Their typical large core and high numerical aperture provide significant advantages over SMFs in applications that require efficient light coupling with large sources and relaxed fiber alignment tolerances. MMFs are used in many fields such as industry, defense, transport, telecommunications and medical. This work focuses on the application for which MMFs are the most widely used nowadays, that is data communications. MMFs have constantly evolved and improved to keep up to pace. The advent of low-cost and low-power-consuming directly current-modulated VCSELs that can reliably support 10Gbps (and more) data rates at ~850nm has motivated the development and the standardization of laser-launch optimized 50µm-diameter GI-MMFs: the OM3 fibers (2002) and the OM4 fibers (2009). We present here the OM3 and OM4 fiber development for the last decade we divided into three main topics:i) the optimization of the refractive index profile to maximize the modal bandwidth (development of the OM4 fiber),ii) the minimization of the macrobending losses (development of so-called bend-insensitive OM4 fibers),iii) the chromatic dispersion compensation to ultimately enlarge the total bandwidth of MMFs, accounting for modal and chromatic dispersions and their interaction

L’émergence et le développement des maladies métaboliques est sous le contrôle de multiples facteurs génétiques et environnementaux. Le diabète et la résistance à l’insuline sont des maladies métaboliques caractérisées par des défauts dans la sécrétion de l’insuline ou son utilisation périphérique, ou les deux. L’insuline est l’hormone clé de l’utilisation du glucose, et régule également transcriptionnellement et épigénétiquement l’expression des gènes.En travaillant sur le muscle, l’implication de l’épigénétique dans la régulation de l’expression des gènes de la voie de l’insuline a été mis en évidence. L’hexokinase 2 (HK2) est régulée par l’insuline et participe au métabolisme glucidique. Le rôle de l’épigénétique y est démontré avec l’augmentation de l’acétylation des histones autour du site d’initiation de la transcription (SIT) de HK2 et l’accumulation d’une isoforme permissive des histones, H2A.Z. Ces deux phénomènes sont le signe d’une transcription permissive.Nous avons ensuite étudié le rôle de l’acétylation des histones dans les régulations amenées par l’insuline dans les myotubes L6. Nous avons utilisé le butyrate, un inhibiteur des histones deacetylase (HDACi), dans un contexte d’insulino-résistance induite par une lipotoxicité. Le butyrate a en partie restauré la sensibilité à l’insuline visible au niveau des phosphorylations de la PKB (protein kinase B) et de la MAPK (Mitogen-activated protein kinase), inhibées par le traitement au palmitate. Le butyrate a augmenté l’expression de l’ARNm et de la protéine d’IRS1. La surexpression génique d’IRS1 est épigénétique-dépendante car liée à une augmentation de l’acétylation des histones au SIT d’IRS1.L’ensemble de ces résultats démontre l’existence d’un lien entre les modifications épigénétique et l’action de l’insuline. Cela suggère qu’une intervention pharmacologique sur la machinerie épigénétique pourrait être un moyen d’améliorer le métabolisme, et l’insulino-résistance
Diabetes and insulin resistance are metabolic diseases characterized by altered glucose homeostasis due to defects in insulin secretion, insulin action in peripheral organs, or both. Insulin is the key hormone for glucose utilization and regulates gene expression via transcriptional and epigenetic regulations.We determined the epigenetic implications in the regulation of expression of insulin signaling pathway genes. Hexokinase 2 (HK2) is known to be upregulated by insulin and directs glucose into the glycolytic pathway. In L6 myotubes, we demonstrated that insulin-induced HK2 gene expression rely on epigenetic changes on the HK2 gene, including an increase in histone acetylation around the transcriptional start site (TSS) of the gene and an increase in the incorporation of the histone H2A.Z isoform – a histone variant of transcriptionally active chromatin. Both are epigenetic modifications compatible with increased gene expression.To elucidate the role of histone acetylation in the regulation of insulin signaling and insulin-dependent transcriptional responses in L6 myotubes, we investigated the effects of butyrate, an histone deacetylase inhibitor (HDACi), in a model of insulin resistance induced by lipotoxicity. Butyrate partly alleviated palmitate-induced insulin resistance by ameliorating insulin-induced PKB (protein kinase B) and MAPK (Mitogen-activated protein kinase) phosphorylations, downregulated with exposure to palmitate. Butyrate induced an upregulation of IRS1 gene and protein expression. The transcriptional upregulation of IRS1 was proven to be epigenetically regulated, with butyrate promoting increased histone acetylation around the TSS of the IRS1 gene.These results support the idea of the existence of a link between epigenetic modifications and insulin action. Pharmacological targeting of the epigenetic machinery might be a new approach to improve metabolism, especially in the insulin resistant condition.Key words: Muscle, insulin resistance, epigenetic, chromatin, histone acetylation, histone deacetylase inhibitor (HDACi), butyrate, palmitate

Thesis (MBA)--Stellenbosch University, 2000.
ENGLISH ABSTRACT: Samancor Chrome is an integrated ferrochrome producer with an estimated annual ferrochrome capacity of 1.26 million tons, or approximately twenty-five per cent of total Western world capacity in 1997. A decline in commodity pricing and other factors prompted Samancor to initiate a business process reengineering (BPR) programme facilitated by McKinsey and Company in the Chrome Alloys Division in 1997. The process however, met with considerable resistance from the Unions within Samancor Chrome, although several strategies were employed to promote acceptance of the process. The technical report assesses the effect of strategies utilised to lessen resistance to change during the business process reengineering programme initiated in Samancor Chrome. The assessment reviewed strategies given in relevant literature to lessen resistance to business reengineering processes and considered the applicability of such strategies within the context of Samancor Chrome. Research data was obtained through semi-structured interviews with Samancor Chrome senior management. The research showed that Samancor Chrome had formulated a communication and a participation strategy in preparation of the BPR programme. The strategies were the only acceptance strategies suggested by McKinsey and Company in their role as the BPR consultants. The context provided by the literature research showed that the participation strategy and the formulation of the communication strategy were inappropriate within the organisational context of Samancor Chrome. Conclusions regarding the situational validity of the strategies were supported by the failure of the strategies to reduce resistance against the BPR programme. A negotiation strategy was ultimately used as an acceptance strategy during the BPR programme, and contextual analysis showed the strategy to be appropriate although only partially effective as implementation was still delayed. Interpretative analysis of the research data indicated that a change management strategy for future BPR initiatives should rather contain elements of education, communication, retrenchment avoidance measures and consultation or negotiation within a management led, top-down approach. Management should drive the BPR process in an emphatic manner, with the programme execution and implementation being completed within a four to six month short time frame.
AFRIKAANSE OPSOMMING: Samancor Chroom is 'n ge-integreerde ferrochroom produsent met 'n geskatte kapasiteit van 1.26 miljoen ton per annum, of ongeveer vyf en twintig persent van die totale Westerse wêreld kapasiteit in 1997. 'n Reële verlaging in kommoditeits pryse sowel as ander faktore het daartoe gelei dat Samancor Chroom in 1997 'n besigheids proses herontwerp oefening onder leiding van McKinsey and Company in die Chroom Allooi Divisie geinisieer het. Die proses is egter deur die Unies binne Samancor weerstaan, alhoewel verskeie strategieë gebruik was om aanvaarding van die proses te bewerkstellig. Die tegniese verslag evalueer die effektiwiteit van die strategieë wat toegepas was om weerstand teen verandering tydens die besigheids proses herontwerp (BPH) in Samancor Chroom te verminder. Die evaluasie neem ook strategieë vanuit toepaslike literatuur om weerstand tydens besigheids proses herontwerp programme te verminder in ag, en oorweeg die toepaslikheid van die strategieë in die konteks van Samancor Chroom. Navorsings inligting is ingesamel deur semi-gestruktureerde onderhoude met Samancor senior bestuurs personeel. Die navorsing dui daarop dat Samancor Chroom kommunikasie en deelnemenings strategieë in voorbereiding vir die BPH program ontwikkel het. Die strategieë was ook die enigste strategieë wat deur McKinsey and Company in hul rol as BPH konsultante voorgestel was. Die konteks deur die literatuur studie geskep, het aangedui dat die deelnemings strategie sowel as die formulering van die kommunikasie strategie onvanpas was binne die organisatoriese konteks van Samancor Chroom. Gevolgtrekkings aangaande die situasionele validiteit van die strategieë was ondersteun deur die faling van die strategieë om weerstand teen die BPH program te verminder. 'n Onderhandelings strategie is uiteindelik as 'n aanvaardings strategie tydens die BPH program toegepas, en konteks analise dui die strategie as toepaslik aan alhoewel slegs gedeeltelik suksesvol, aangesien die program implementasie vertraag was. Interpretiewe analise van die navorsings inligting dui aan dat 'n veranderings strategie vir toekomstige BPH initiatiewe elemente van opleiding, kommunikasie, inkorting vermyding maatreëls en konsultasie of onderhandeling binne 'n bestuurs gedrewe program benadering moet bevat. Die program moet sonder vertraging gedryf word, met program voltooing en implementering tussen vier tot ses maande.

This thesis is about the role of The Facilitates Chromatin Transcription (FACT) complex as a potential target for Neuroendocrine Prostate Cancer (NEPC). I studied FACT complex in different models representing the main stages of prostate cancer progression and found that FACT complex expression correlated to the lethal NEPC phenotype. The FACT-inhibiting drug, CBL1037, was more effective at reducing cell viability as compared to the standard-of-care chemotherapy drugs, cisplatin and carboplatin. Significantly lower dose of CBL0137 was required to achieve 50% cell death. These results are promising and support further investigation of CBL0137 as anti-cancer therapy in late-stage prostate cancer.

Afin d'améliorer les propriétés de résistance à l'usure par abrasion et à la fatigue des aciers à 5% de chrome, nous intégrons à la gamme de traitements thermiques de l'acier à outils Z38CDV5. 3, les traitements thermochimiques de carburation et de nitruration. Les traitements thermochimiques de carburation et de nitruration sont réalisés en phase gazeuse à la pression atmosphérique respectivement par le propane et par l'ammoniac. Le traitement de carburation se décompose en deux étapes : - une première étape qui correspond à l'enrichissement en carbone en phase austénitique. La cinétique d'enrichissement est corrélée aux stades de précipitation des carbures M₃C, M₃C+M₇C₃et M₇C₃. - une seconde étape qui correspond à la diffusion du carbone en phase austénitique (enrichissement nul). La nature des carbures évolue et la durée de la période de diffusion dépend de l'état microstructural visé : état équivalent par exemple à l'acier Z100CDV5. La modélisation des phénomènes de diffusion du carbone en solution solide austénitique, permet de calculer les durées d'enrichissement et de diffusion en fonction de la concentration en carbone, la nature de la précipitation et de la profondeur carburée visées. Les ultimes traitements de revenu et de nitruration, permettent de définir une gamme optimisée de traitements thermochimiques réalisable dans un même réacteur et facilement transposable en milieu industriel. L’acier Z38CDV5. 3 intégralement traité par cette procédure, présente une résistance à l'usure par abrasion supérieure à celle de l'acier rapide 6 - 5 - 2. Le traitement de carburation d'aciers alliés à 5% de chrome montre ses potentialités pour développer des microstructures particulièrement adaptées à la résistance à l'usure.

L'etude de la chloruration seche du titane et du chrome effectuee dans une atmosphere statique de chlore a permis d'etablir les diagrammes temperature-pression delimitant les differents domaines de cinetiques reactionnelles. La finalite de l'etude est d'acceder au comportement d'alliages resistants a la corrosion par le chlore a partir des connaissances acquises sur les metaux purs. Dans le cas du titane, l'etude a ete etendue au titane nitrure par plasma d'ammoniac expose a la corrosion par le chlore sec et a la corrosion humide par l'acide sulfurique

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Os impactos ambientais causados por sucessivas extrações de minérios e compostos gerados dos resíduos tóxicos dessa atividade têm sido foco de preocupação dos ambientalistas, neste contexto há um grande esforço gerado para o desenvolvimento de metodologias eficientes e de baixo custo para remoção de metais pesados de solos e águas contaminadas. Os métodos biológicos surgem como uma alternativa aos métodos convencionais para o solo, um dos ecossistemas terrestre que apresentam uma infinidade de recursos naturais além da grande diversidade de microrganismos interagindo entre si. O mesmo constitui fonte de investimento para o isolamento de microrganismos e análises metagenômicas para prospecção de genes envolvidos em processos importantes para o equilíbrio metabólico e ecológico, pois, tanto de maneira isolada, como em interações, estes organismos desempenham papel importante no que diz respeito à produção de enzimas na biorremoção de metais e contaminantes do solo. Este trabalho teve como objetivo isolar, caracterizar e avaliar a biossorção e bioacumulação de metais por microrganismos originados de solos de ecossistemas de Sabará, uma região de mineradora desativada Minas Gerais. Adicionalmente buscou-se avaliar a diversidade metabólica funcional, para uma comparação da microbiota de, Sabará e Brumadinho, combinada com busca de genes que conferem resistência a cromo (crhA), cobre (copA, copB, cueO) e níquel (nixA). Os isolados obtidos foram classificados em gêneros como Burkolderia, Serratia, Bacillus, Stenotrophomonas e Artrobacter, que apresentam potencial para biorremediação de metais do solo e água. Entretanto, seis dos 32 isolados apresentaram resistência aos metais cobre, cromo e níquel, na concentração de 500 mgL-1. Destes isolados, dois deles, do gênero Burkolderia e Arthrobacter (CP15 e CR11) apresentaram capacidade metabólica de biossorver e interiorizar metais pesados em diferentes fases do desenvolvimento. Quanto a atividade metabólica, a comunidade microbiana dos solos do perímetro do quadrilátero ferrífero (MG) tem alta atividade na degradação de fontes de carbono importantes nos ciclos biogeoquímico e biorremediação, justificando a grande quantidade de ORFs encontradas nas anotações do metagenoma sequenciado. Destaca-se os ecossistemas canga e floresta que apresentaram maior número de sequências identificadas para todos os genes envolvidos no processo de resistência, influxo e efluxo de metais, sendo eles genes de resistência a cobre, multicooper oxidase ATPase (copA, copB, cueO), multicopper ATPase like (copA, copB), cromo oxidase (chrA), cromo transporte (chrB) e níquel oxidase (nixA). Os solos da região de Sabará e Brumadinho alocados no, quadrilátero ferrífero, apresentam diversidade funcional para degradação de fontes de carbono como aminoácidos e compostos fenólicos, e genes funcionais de grande importância em processos metabólicos de remoção de metais pesados por microrganismos, além de microbiota com capacidade remover e interiorizar metais oriundos dos resíduos de mineração sendo um indicativo para a aplicação na biorremediação de metais em áreas afetadas pela mineração.
The environmental impacts caused by successive extractions of minerals and compounds generated toxic waste of this activity have been the focus of concern for environmentalists in this context there is a great effort generated for the development of efficient methodologies and cost-effective to remove heavy metals from soils and contaminated water. Biological methods appear as an alternative to conventional methods for the ground of the earth's ecosystems have a multitude of natural resources beyond the great diversity of microorganisms interacting. The same is investment source for the isolation of microorganisms and metagenomic analyzes to search for genes involved in important processes for metabolic and ecological balance, since both in isolation, as in interactions, these organisms play an important role as regards the production of enzymes in biorremoção metal and soil contaminants. This study aimed to isolate, characterize and evaluate the biosorption and bioaccumulation of metals by microorganisms originating from Sabara ecosystems soil, a mining region of Minas Gerais disabled. In addition we sought to evaluate the functional metabolic diversity, for a comparison of the microbiota of Sabara and Brumadinho, combined with search of genes that confer resistance to chromium (CRHA), copper (copA, CopB, cueO) and nickel (Nixa). The isolates were classified into genres such as Burkolderia, Serratia, Bacillus, Stenotrophomonas and Artrobacter, which have the potential for bioremediation of metals from soil and water. However, six of the 32 isolates were resistant to metals copper, chromium and nickel, at a concentration of 500 mg L-1. Of these isolates, two of them, the genus Arthrobacter and Burkolderia (CP15 and CR11) had metabolic capacity to internalize biossorver and heavy metals at different stages of development. As metabolic activity, the microbial community of the perimeter of iron quadrangle soils (MG) has high activity in the degradation of important carbon sources in biogeochemical cycles and bioremediation, which explains the large amount of ORFs found in the notes of sequenced metagenome. the yoke ecosystems and forest that had a greater number of sequences identified for all the genes involved in the resistance process is noteworthy, influx and efflux of metals, and they copper resistance genes, multicooper oxidase ATPase (copA, copB, cueO) multicopper ATPase like (copA, CopB), chrome oxidase (chrA), chrome transport (chrB) and nickel oxidase (nixA). The soils of Sabara and Brumadinho region allocated to, iron quadrangle, have functional diversity for degradation carbon sources such as amino acids and phenolic compounds, and functional genes of great importance for metabolic processes of removing heavy metals by microorganisms, and microorganisms with ability to remove and internalize metals coming from the waste mining being an indication for use in the bioremediation of metals in areas affected by mining.
FAPESP: 2012/20022-6

Cette étude fondamentale est dédiée à la compréhension de l’influence de la composition chimique, notamment la teneur en chrome, des alliages base de nickel sur leur mécanismes de corrosion et d’oxydation. La corrosion sous contrainte intergranular (CSCIG) est un mode de dégradation qui affecte de nombreux alliages au sein des réacteurs à eau pressurisé. En particulier, les alliages base nickel tubes des générateur de vapeur (GV). La sensibilité à la CSC est désormais dépend de la teneur en chrome, ce qui a conduit au remplacement de l’alliage 600 (Ni-16Cr-9Fe) par l’alliage 690 (Ni-30Cr-9Fe). Cependant le bon comportement de l’alliage 690 en termes de résistance à la corrosion restes mal défini. L’objective de cette thèse est double : i) déterminer l’effet de la teneur en chrome, ii) contribuer à la compréhension de l’effet de fer étant un élément d’addition sur la résistance à la corrosion et l’oxydation généralisée des alliages base nickel en milieu primaire assimilé et en vapeur surchauffée à 700°C. Par ailleurs, des analyses électrochimiques pertinentes dans la température ambiante ont été mené afin d’établir une corrélation entre les propriétés physiques de film passive susceptible de protéger le matériau et de la teneur en chrome. Des alliages modèles binaires Ni-Cr, à teneur de chrome varie entre 14 et 30 % en poids, des alliages ternaires Ni-Cr-8Fe et l’alliage 600 ont été étudies. L’aspect expérimental de cette étude repose sur des techniques conventionnelles: SEM, STEM, EDX, Potentiodynamique, EIS, Chronoamperometrie, Mott-Schottky. La cinétique d’oxydation en vapeur surchauffée a été déterminée en mesurant l’apport de masse. L’impact de l’état de surface sur le processus de la corrosion et l’oxydation a été mis en évidence. Les polissages miroir et électrochimique ont été réalisés afin de découpler l’effet de l’écrouissage développé en subsurface, induit par la préparation de surface, et la composition chimique de l’alliage. La teneur en chrome limite à partir de laquelle l’alliage a un comportement satisfaisant en corrosion a été déterminé à 20% dans le milieu primaire. Cependant les analyses électrochimiques ont décelé l’existence d’une teneur en chrome optimal à 26%. La cinétique d’oxydation des alliages modèles ainsi que la morphologie des oxydes formés sur ces matériaux dans le milieu vapeur surchauffée ont indiqué l’existence d’une teneur en chrome optimal à 24%. Une dégradation des propriétés des films d’oxydes a été observée en augmentant la teneur en chrome au-dessus de l’optimum. En résumé, ce travail se préoccupe de l’optimisation de la teneur en chrome, méthode plus adéquate, pour l’amélioration de la résistance à la corrosion et l’oxydation des alliages base nickel
This fundamental study is focused on the understanding of the influence of the chemical composition of Ni-based alloys on their corrosion and oxidation mechanisms. This work is not dedicated for a particular application. It is well known for instance that Ni-based alloys are susceptible to intergranular stress corrosion cracking (IGSCC) in primary water. Thus, Alloy600 (Ni-16Cr-9Fe), used in steam generator (SG) tubing, was replaced by higher chromium content material Alloy690 (Ni-30Cr-9Fe). This later shows a better resistance to IGSCC which may be linked to the growth of more protective oxide layer as chromium content is increased to 30 wt.%. The main goal of this study is to investigate: i) the influence of chromium content, ii) impact of iron addition on the corrosion and oxidation resistance of Ni-based alloys in primary water and superheated steam at 700°C. Furthermore, analytical approach in acidic solution is conducted at room temperature. This allowed to establish a relationship between alloying elements and physical properties of the oxide layers. For this purpose, Ni-xCr (14 ≤ x≤ 30 wt.%), Ni-xCr-8Fe (x=14,22 and 30 wt.%) model alloys and industrial material Alloy600 have been studied. To characterize the oxide scales, conventional technics were used: SEM, STEM, EDX, Potentiodynamic, EIS, Chronoamperometry, Mott-Schottky. Furthermore, steam oxidation kinetics was evaluated by means of weight gain measurements. To uncouple the effect of surface cold-work and the chemical composition of the base metal, mirror and electro polishing were carried out. In primary water, critical chromium content (20 wt.%), which corresponds to the minimum amount of chromium required to the transition from non-protective to protective and compact Cr-oxide layer, is determined. However, the analytical approach, using electrochemical technics, at room temperature elucidated the existence of optimum chromium content (26 wt.%) in terms of corrosion resistance. In superheat steam, oxidation kinetics and oxide scale characteristics showed the existence of optimum chromium content (24 wt.%) in terms of oxidation resistance. The corrosion and oxidation resistance is degraded as chromium content was increased more than optimal amount. Iron addition (8 wt.%) had a detrimental effect on the protectivess of the resulting oxide scales. Finally, this study showed that optimizing of chromium content is more appropriate method for enhancing corrosion and oxidation resistance, that increasing chromium content to high level is not necessary beneficial to those parameters. This work provides a useful knowledge to design new alternative materials. For this purpose, more investigations should be conducted to test other parameters such as: weldability, fabricability, thermal conductivity,etc

Робота присвячена дослідженню впливу одного з ефективних способів зміцнення поверхні сталі У8А - хіміко-термічній обробці а саме після процесу дифузійного хромування попередньо азотованих сталей. Проаналізовано вплив сформованого комплексного карбідного та нітридного покриття на зносостійкість сталі У8А. Розроблене нове програмне забезпечення яке дозволяє спрогнозувати велечину зносу сталі У8А після хіміко-термічної обробки.

Робота присвячена дослідженню мікроструктури, механічних властивостей та характеристик сталі 12Х18Н10Т після хіміко-термічної обробки, а саме після дифузійного одночасного насичення кремнієм та хромом. Доцільність використання даного типу покриття на сталі 12Х18Н10Т підтверджена випробуваннями на розтяг. Стійкість сталі 12Х18Н10Т до міжкристалічної корозії доведена експериментом. Підтверджена перспективність даного типу покриття як зносотійкого.
The work is devoted to the study of the microstructure, mechanical properties and characteristics of steel 12Х18Н10Т (AISI 321) after chemical-heat treatment, namely after diffusion simultaneous saturation with silicon and chromium. The feasibility of using this type of coating on steel 12X18H10T (AISI 321) is confirmed by tensile tests. The resistance of steel 12Х18Н10Т to intergranular corrosion was proved experimentally. The confirmed are prospects of this type of coating as wear-resistant.

L’objectif de ce travail est d’étudier la croissance de films minces de Ti, TiO2, Cr et CrN sur des fils en acier inoxydable 316L, afin de conférer des nouvelles propriétés à ces fils. Une technologie originale a été développée pour revêtir ces fils au défilé avec la mise au point d’une chambre de nettoyage, suivie d’une chambre de dépôt constituée par un magnétron cylindrique inversé, afin d’assurer l’uniformité des dépôts sur un substrat de géométrie circulaire. Des couches minces de TiO2 ont été déposées afin d’obtenir des couleurs d’interférence de ces fils utilisés dans l’architecture. Les revêtements CrNx ont été étudiés en vue de remplacer le chromage électrolytique. Les analyses XPS, DRX, MEB et MET-ASTAR mettent en évidence la complexité des structures obtenues sur le plan morphologique, chimique et structural.Les structures obtenues au défilé sont corrélées aux paramètres du procédé tels que la température et le champ magnétique. Pour une cathode avec un champ magnétique hétérogène, un empoisonnement partiel de la cible est alors constaté lors de l’augmentation du flux de dioxygène, permettant l’élaboration de multicouches (Ti/TiO2) lors d’un seul passage dans la cathode. Les revêtements à base de TiOx présentent des gradients chimiques et structuraux en section transverse dus aux hétérogénéités du plasma au sein de la cathode cylindrique. La mise au point d’une seconde cathode comportant un champ magnétique plus homogène a permis l’obtention de couches métalliques de chrome plus homogènes dans l’épaisseur d’un point de vue chimique et structural. La pulvérisation réactive a été validée avec des dépôts de CrNx restant également homogènes dans l’épaisseur lors de l’augmentation du flux d’azote.L’influence de la température de dépôt sur la microstructure du Ti, TiO2, Cr et CrN a été étudiée. Des cartographies de phases et d’orientation MET-ASTAR, combinées avec des études par DRX et EDS, ont permis l’identification de phases atypiques lors de l’élaboration de dépôts à des températures voisines de 550 °C. Ainsi, ces dépôts de Ti présentent des phases de Laves ; tandis que ceux de Cr présentent du Cr quasi-amorphe, du FeCr tantôt stable (DRX), tantôt métastable (MET). L’étude des dépôts de TiO2 élaborés à des températures > 500 °C révèlent une oxydation de la surface de l’acier.Enfin, les propriétés d’usage comme la coloration, les propriétés mécaniques ou la durabilité sont présentées. Le résultat marquant de cette thèse est de montrer expérimentalement que la résistance à la corrosion localisée en milieu chloruré de ces fils revêtus est pilotée au premier ordre par le substrat. Les revêtements déposés, bien que plus nobles que le substrat, ne constituent pas une barrière efficace car ils comportent des défauts comme des porosités ou encore des manques de recouvrement. Il a été aussi mis en évidence des modifications du film passif de l’acier inoxydable 316L lors d’études utilisant la pulvérisation de ces fils pour simuler les modifications de la surface de l’acier lors de la croissance des couches minces. Ces modifications dégradent la résistance à la corrosion par piqûre des fils d’autant plus que la température est élevée et que l’atmosphère est réactive. Pour des températures > 500 °C et dans une atmosphère d’argon et d’oxygène, la surface de l’acier est constituée d’une couche d’oxyde de plusieurs dizaines de nm alors qu’elle est constituée d’une couche d’oxyde de fer dans une atmosphère d’argon et d’azote. Les études électrochimiques montrent une dégradation de la résistance à la corrosion de ces fils d’acier inoxydable, cette dégradation devient même catastrophique lorsque ces fils sont pulvérisés dans des atmosphères réactives et à des températures élevées. La résistance à la corrosion localisée des substrats revêtus montrent la même évolution validant ainsi l’importance des modifications des films passifs en fonction de la température et des atmosphères de pulvérisation lors de l’élaboration des revêtements
The objective of this work is to study the growth of Ti, TiO2, Cr, and CrN thin films on 316L stainless steel wires, in order to functionalize these wires. An original technology has been developed to coat these moving wires with the development of a cleaning chamber, followed by a deposition chamber constituted by an inverted cylindrical magnetron, to ensure the uniformity of coatings on a substrate of circular geometry. Thin films of TiO2 have been deposited to obtain interference colors from these wires, used in architecture. CrNx coatings have been developed to replace electrolytic chrome plating. Studies of XPS, XRD, SEM and TEM-ASTAR highlight the morphological, chemical and structural complexity of the coatings.The structures are correlated with the process parameters such as the temperature and the magnetic field. For a cathode with a heterogeneous magnetic field, partial poisoning of the target is then observed during the increase in the oxygen flow, allowing the development of multilayers (Ti/TiO2) during a single pass through the cathode. TiOx-based coatings exhibit chemical and structural gradients in cross section, due to plasma heterogeneities within the cylindrical cathode. The development of a second cathode with a more homogeneous magnetic field has enabled the possibility to obtain a more homogeneous in thickness metallic layer of chromium, from a chemical and structural point of view. Reactive sputtering deposition has been validated with deposits of CrNx, also remaining homogeneous throughout their thickness as the nitrogen flow increases.The influence of deposition temperature on the microstructure of Ti, TiO2, Cr and CrN was studied. TEM-ASTAR phase and orientation mappings, combined with DRX and EDS studies, have enabled the identification of atypical phases during the development of deposits at temperatures around 550 °C. Thus, these Ti films exhibit Laves phases; while those of Cr present quasi-amorphous Cr, sometimes stable FeCr (DRX), sometimes metastable (MET). The study of TiO2 deposits produced at temperatures > 500 °C reveals oxidation of the steel surface.Finally, the use properties such as coloring, mechanical properties or durability are presented. The outstanding result of this thesis is to show experimentally that the resistance to localized corrosion of these coated wires is controlled in the first order by the substrate, in a chlorinated medium. The coatings, although more noble than the substrate, do not constitute an effective barrier, because they have defects such as porosities or even lack of coverage. Changes in the passive film of 316L stainless steel have also been shown by sputtering these wires to simulate changes in the steel surface as coatings are grown. These modifications degrade the pitting corrosion resistance of the wires as the temperature increases and the atmosphere is reactive. For temperatures > 500 °C and in an atmosphere of argon and oxygen, the surface of the steel consists of an oxide layer of several tens of nm, while it consists of a layer of iron oxide in an atmosphere of argon and nitrogen. Electrochemical studies show a degradation in the corrosion resistance of these stainless steel wires, this degradation even becomes catastrophic when these wires are sputtered in reactive atmospheres and at high temperatures. The resistance to localized corrosion of the coated substrates shows the same evolution, thus validating the importance of the modifications of the passive films as a function of the temperature and of the atmospheres during the development of the coatings and during the sputtering of the wires

La compréhension des phénomènes d'oxydation à haute température des alliages base nickel revêt un intérêt particulier pour l'industrie nucléaire. Les performances de ces alliages, tout comme celles des aciers, sont fortement influencées par les différents éléments mineurs d'addition. Six alliages commerciaux ont été traités entre 800°C et 1000°C sous air et étudiés à l'aide des méthodes d'analyse complémentaires suivantes : spectroscopie de photoélectrons induits par un rayonnement X, spectroscopie infrarouge à transformée de Fourier, diffraction des rayons X et microscopie électronique à balayage couplée avec un système d'analyse en énergie des rayons X émis. Les résultats obtenus mettent en évidence le rôle très important des éléments mineurs d'addition que sont le manganèse, le silicium, le titane, l'aluminium et le niobium sur les mécanismes d'oxydation. La diffusion rapide du manganèse et du titane à travers la phase rhomboédrique formée initialement, conduit à la formation d'une couche d'oxydes de structure duplex. L'oxydation intergranulaire du titane et de l'aluminium est substantielle et peut être corrélée avec l'épaisseur de la zone affectée par la déplétion en chrome dans l'alliage sous-jacent. Le silicium favorise la formation du chromite de manganèse, cependant, le développement d'une couche continue de silice à l'interface oxyde-alliage ralentit la cinétique d'oxydation. La présence de niobium semble également avoir un effet bénéfique sur la résistance à l'oxydation. La comparaison de ces résultats avec ceux obtenus sur des aciers ferritiques et austénitiques étudiés au laboratoire et avec ceux issus de la littérature permet d'apporter des informations qualitatives concernant la vitesse de diffusion des différents éléments en fonction de la matrice. Ainsi, dans les aciers ferritiques, ou les vitesses de diffusion sont plus élevées que dans les matrices austénitiques, la diffusion du titane est plus rapide que celle du manganèse. Dans les aciers austénitiques, ces deux éléments diffusent à des vitesses comparables alors que dans les alliages base nickel, le manganèse diffuse plus vite que le titane.

Hexavalent chromium [Cr(VI)] is considered an environmental priority pollutant for both its high dangerousness towards human health and its wide diffusion. In contrast, the trivalent form of chromium [Cr(III)] is much less toxic and insoluble. Hence, the basic process for chromium detoxification is the transformation of Cr(VI) to Cr(III). Bioremediation, exploiting microorganisms' ability to reduce Cr(VI) to Cr(III), represents a considerable alternative to traditional physic-chemical technologies, which are uneconomical, mainly for treatment of wide contaminated sites, and can create, in turn, environmental problems. A noticeable contribution to develop an efficient bioremediation approach can be provided by the use of microbial biofilm. Biofilms, the form commonly taken by microorganisms in environment, are able to contrast environmental stress (nutrient limitation, sudden pH changes, toxic compounds, etc.) and to detoxify contaminants more efficiently than microorganisms grown under planktonic conditions. Pseudomonas alcaliphila 34 is a chromate hyper-resistant and biofilm-producing bacterium, previously characterized in terms of hundreds of biochemical attributes and its chromate-reducing capability in the presence of different carbon/energy sources, and proposed for bioremediation processes. In this work Pseudomonas alcaliphila 34 was investigated in order to give a significant contribution to the development of an efficient biological system for the remediation of chromate contaminated soils. The general aim of the project was reached with the achievement of the following intermediate objectives: i. The development of a procedure, combining the Calgary Biofilm Device (MBEC device) and Phenotype MicroArray (PM) technology, for a wide-scale analysis of toxic chemicals susceptibility of biofilm and planktonic culture. ii. The sequencing, assembling and annotation of P. alcaliphila 34 genome. iii. The investigation of molecular bases implicated in chromate resistance and biofilm development in P. alcaliphila 34 strain by transcriptome analysis. The development of an integrated system combining two high-throughput technologies, MBEC device/PM, offered the possibility to obtain an extensive characterization of toxic compounds susceptibility of P. alcaliphila 34 biofilm and planktonic culture. The common assumption that biofilms are more tolerant than planktonic cells was confuted and was showed that cultures in the stationary phase were often more tolerant than biofilms in presence of the majority of chemicals used. Therefore, any conclusions regarding biofilm and planktonic culture resistance should take into account the growth phase of planktonic cultures and the nature of chemicals. Annotation of P. alcaliphila 34 genome allowed the identification of 4,983 protein-coding sequences and 61 tRNAs. Genome analysis indicated that P. alcaliphila 34 possesses a putative chrBACF operon that is involved in the high chromate resistance of the bacterium. Mercuric and arsenic resistance operons and many genes encoding putative multidrug resistance efflux systems were also identified on the genome. From temporal genomic profiling of P. alcaliphila 34 planktonic cultures exposed to an acute chromate stress the overexpression of genes involved in sulfur metabolism was highlighted, as well as the activation of oxidative stress response system and mechanism related to DNA repair. The chromate shock response of P. alcaliphila 34 was also characterized by the enhanced expression of genetic pathways relative to iron acquisition and metabolism, and the down-regulation of copper metabolism, suggesting a correlation between chromate exposure and the pathways of these two metals. The analysis of differentially expressed genes related to the early developing P. alcaliphila 34 biofilm revealed the induction of the pathway involved in flagellar motility and the down-regulation of a type IV pilus metabolic system. Interestingly, from the transcriptomic analysis of P. alcaliphila 34 response to an acute chromate challenge, the presence of pathways involved in biofilm formation has emerged. This observation indicates that biofilm formation may be a survival strategy to deal with chromate. In conclusion, obtained data have shown that : • the MBEC device/PM approach is a reliable, repeatable, accurate, and quick method to evaluate the effect of toxic chemicals (i.e., antibiotics, biocides, heavy metals) on metabolic activity of microbial biofilms; • the acquired know-how indicated that it is necessary to determine at what stage of growth the microorganism shows the best fitness in presence of a given pollutants to plan bioremediation processes; • the transcriptomic analysis provided insights into the molecular mechanisms related to biofilm development and chromate resistance. Furthermore, the obtained information may be used to design a biological system for bioremediation of chromate contaminated soils using biofilm of the highly Cr(VI)-resistant P. alcaliphila 34 strain.

碩士
國立成功大學
材料科學及工程學系
89
This study simulated the work conditions in the smelting reduction processes for high corrosion between refractories and slags with high FeO content, low basicity 1and low carbon content1 at 1650℃. The relationship between test temperature, time and molten-slag corrosion, the corrosion resistance mechanism was discussed. The corrosion test was determined by using dynamic rotary slag corrosion and electric furnace static slag corrosion tests. The magnesia-chrome refractory specimens were investigated by X-ray diffraction, optical polarized microscope, scanning electron microscope (SEM), energy dispersive spectrometer (EDS), mapping, line scanning, scanning transmission electron microscope (STEM) and electron diffraction (ED) patterns after corrosion test. The excellent corrosion resistance with only 1% eroded area was obtained for the magnesia-chrome bricks after dynamic rotary slag corrosion test at 1650℃ for 9 cycles. The penetration layer of 20 mm formed in the magnesia-chrome bricks specimens. The open porosity about 4 % and pore size about 6μm in the penetration layer were lower and smaller than that of origin bricks. After electric furnace static slag corrosion test, XRD result shows that the MgO content in the penetration layer decreased with increasing test temperature and time. And further, it reacted with SiO2 and CaO to form CaMgSiO4 compound which was met and propagated along the crack into the slag. After electric furnace static slag corrosion test, a diffusion layer between magnesia-chrome brick and slag was formed. The thickness of diffusion layer increased with increasing test time. From TEM analysis, the diffusion layer was (Mg,Fe)(Al,Cr)2O4 solid solution which bounded well with MgCr2O4 phase.

The past few decades have witnessed an array of advances in DNA science including the introduction of genomics and bioinformatics. The quest for complete genome sequences has driven the development of microarray and massively parallel sequencing technologies at a rapid pace, yielding numerous scientific discoveries. My thesis applies several of these genome-scale technologies to understand genomic response to perturbation as well as chromatin structure, and it is divided into three major studies. The first study describes a method I developed to identify drug targets by overexpressing human genes in yeast. This chemical genomic assay makes use of the human ORFeome collection and oligonucleotide microarrays to identify potential novel human drug targets. My second study applies genome resequencing of yeast that have evolved resistance to antifungal drug combinations. Using massively parallel genomic sequencing, I identified novel genomic variations that were responsible for this resistance and it was confirmed in vivo. Lastly, I report the characterization of chromatin structure in a non-eukaryotic species, an archaeon. The conservation of the nucleosomal landscape in archaea suggests that chromatin is not solely a hallmark of eukaryotes, and that its role in transcriptional regulation is ancient. Together, these 3 studies illustrate how maturation of genomic technology for research applications has great utility for the identification of potential human and antifungal drug targets and offers an encompassing glance at the structure of genomes.

Лямцева А. О. Формування структурного стану та властивостей двофазних корозійностійких сталей при високотемпературній цементації : кваліфікаційна робота магістра спеціальності 105 "Прикладна фізика та наноматеріали" / наук. керівник В. Г. Міщенко. Запоріжжя : ЗНУ, 2020. 52 с.
UA : Робота викладена на 52 сторінках друкованого тексту, містить 6 таблиць, 27 рисунків, 44 джерела. Об’єкт дослідження –двофазна корозійностійка сталь 06Х18ч. Мета роботи – дослідження структури та властивостей двофазної сталі 06Х18ч при різному термічному обробленні. Метод дослідження – металографічний, дюрометричний. Значимість роботи – результати залежності кількості вуглецю у хімічному складі зразка від твердості поверхневого шару двофазної корозійностійкої сталі дають можливість використовувати сталь при умовах роботи в середовищі з підвищеними механічними та експлуатаційними навантаженнями. Результати роботи рекомендується використовувати для оцінки придатності матеріалу при його використанні в певних умовах роботи. У кваліфікаційній роботі було досліджено механічні та службові властивості корозійностійкої сталі 06Х18ч в залежності від різних режимів термічного оброблення. За результатами металографічного аналізу визначено, що при певній термічній обробці механізмом зміцнення для даних сталей є виділення карбідної фази. Зі збільшенням вмісту виділення карбідів по границям зерен більш рівномірне, в результаті чого отримаємо більш високі показники твердості.
EN : The work is presented on 52 pages of printed text, 6 table, 27 figures, 44 references. The object of research is duplex steel 06Х18h. The purpose of the work is to study the structure and properties of duplex steel 06Х18ч at different heat treatment. Research method - metallographic, durometric. Significance of work - the results of the dependence of the amount of carbon in the chemical composition of the sample on the hardness of the surface layer of duplex stainless steel make it possible to use steel under operating conditions in environments with high mechanical and operational loads. It is recommended to use the results to assess the suitability of the material when used in certain operating conditions. In the qualification work the mechanical and service properties of stainless steel 06Х18ч depending on different modes of heat treatment were investigated. According to the results of metallographic analysis, it is determined that at a certain heat treatment the mechanism of hardening for these steels is the release of the carbide phase. With increasing content of carbides on the grain boundaries is more uniform, resulting in higher hardness values.