Дисертації з теми "Tin-lead alloy"

There remains a wide variety of evidence for the production and co~sumption of tin and lead alloy tableware in Roman Britain. In this thesis it is the categorisation of RomanoBritish tin and lead alloy tableware, as well as vessel production moulds, manufacturing debris and compositional data for pewter vessels that forms the study's foundation. Yet it is the main purpose of this thesis to place this data in a wider social, economic' and chronological context. In particular two powerful theoretical perspectives - that social identities could be constructed through the consumption of 'objects', and that such identities can be recorded in an object's depositional context - have informed this research. The main result of this study is that pewter tableware, although a 'Romanized' material, could create and maintain a range of different social identities. Functionally different vessels, for example, can be taken as indicators of different 'lifestyle' choices, the comparative values of which shifted over time. However, these identities could also be renegotiated over time to suit a number of 'atypical' personal choices, such as the reuse of high status vessels in ritual or low status roles. Another key result is that pewter consumption was also constrained by a comparative absence of tin in Britain before the 3'1 century. Limited pre-3rt! century pewter production can be suggested as occurring predominandy where there was easy access to imported tin. However, post 3rt! century production, although most prolific in regions that had direct access to Cornish tin, could also exist in central and eastern England where they were fuelled by recycled tin, the extent of which is starting to be addressed through compositional analysis of Romano-British pewter. These findings, and the data they are built on, should both contribute to research on Romano-British pewter, and more generally provide new approaches to understand Roman material culture in Britain.

Thesis (Ph. D.)--Chemistry and Biochemistry, Georgia Institute of Technology, 2008.
Committee Chair: Dr. C. P. Wong; Committee Member: Dr. Boris Mizaikoff; Committee Member: Dr. Rigoberto Hernandez; Committee Member: Dr. Z. John Zhang; Committee Member: Dr. Z.L. Wang.

>Magister Scientiae - MSc
Organic-inorganic lead-based perovskite has exhibited great performance in the past few years. However, the lead (Pb) embedded in those compounds is a significant drawback to further progress, due to its environmental toxicity. As an alternative, tin (Sn) based-perovskites have demonstrated promising results in terms of electrical and optical properties for photovoltaic devices, but the oxidation of tin ion- from stannous ion (Sn2+) to stannic ion (Sn4+) presents a problem in terms of performance and stability when exposed to ambient conditions. A more feasible approach may be in a Pb-Sn binary metal perovskite in pursuit of efficient, stable perovskite solar cells (PSCs) with reduced Pb-content, as compared to pure Pb- or Sn-based PSCs. Here, we report on the deposition of a Pb-Sn binary perovskite by sequential chemical vapor deposition.

Traditionally, lead-based bearing overlays dominate the commercial automotive market and it has been proven that an excellent combination of properties can be attained through their use. However, lead is a toxic metal and a cumulative poison in humans. According to the European Union End-of-Life Vehicle (ELV) Directive proposed in 1997, vehicles that registered in'all the member states after 1st July 2003 should contain no lead, mercury, cadmium and hexavalent chromium. In this study, a new sulphate-gluconate electrolyte was used to produce multilayer SnCo coatings, aimed at a lead-free overlay for future market use. Tin-cobalt compositionally modulated alloy (CMA) coatings produced from sulphategluconate electrolytes have been previously examined as a potential replacement for lead-free bearing overlays [1]. However, some obstacles may exist which limit their potential use on an industrial scale. For example, long electroplating times are required to produce a thick coating which is very undesirable from an industrial viewpoint, and also the possible elemental interdiffusion occurring in the coating system under engine operating temperatures could rapidly deteriorate the coating properties. In addition, there is an increasing demand from automotive industry to further improve bearing overlay properties, for example for high performance and high compression ratio engines.

Two types of solder samples, pins and through-holes were tested by SERA™ (Sequential Electrochemical Reduction Analysis) and Wetting Balance after various length of steamaging treatment. It was shown that after steam-aging, both types of specimen gave a similar electrochemical reduction curve, and solderabilty predictions made from SERA™ test agree with results obtained from Wetting Balance test on a qualitative base. Wetting balance test of pin samples after SERA™ test confirmed that SERA™ is a non-destructive testing method -- it even restored solderability. Comparison of electrochemical reduction behavior of samples under different treatment indicates that steam-aging can not reproduce exactly the effect of naturally atmospheric aging, and may not be the best artificial accelerating environment adopted.

Дипломна робота: 86 с., 20 рис., 30 табл., 16 посилань. Мета роботи – оптимізація технологічних процесів відтворення у металі копій двох художніх виробів за наявними неметалевими оригіналами. Методика дослідження – виготовлення силіконових та гіпсових прес-форм із різними варіантами ливникової системи; виготовлення гіпсо кремнеземистих ливарних форм, їх прожарювання та заливання при різних температурах; контроль параметрів якості виливків (шорсткість поверхонь та наявність ливарних дефектів). Результати та їх новизна – теоретично і практично установлено придатність силіконових прес-форм для виготовлення якісних виливків із легкоплавких (олов’яно-свинцевих) сплавів; досліджено параметри технологічних процесів відтворення у металі копій художніх виробів; виготовлено серію якісних художніх виливків із олов’яно-свинцевого і мідного сплаву. Основні показники – в результаті виконання роботи визначено оптимальні параметри технологічних процесів виготовлення художніх виробів. Відлито статуетку «Вікінг» масою 0,099 кг із олов’яно-свинцевого сплаву та масою 0,073 к із латуні Л63, а також статуетку «Кельт» масою 0,468 кг із латуні Л63. Вироби не мають ливарних дефектів, шорсткість поверхонь виливка «Кельт» не перевищує 12,5 мкм, а «Вікінг» - 6,3 мкм. Область застосування – Художнє та ювелірне литво унікальних виробів. Економічна ефективність – 214 137,4 грн. Прогнозні припущення щодо розвитку об’єкта дослідження – за аналогією із дослідженими технологічними процесами, розроблення схем виготовлення схожих за розмірами та складністю литих художніх виробів в умовах дрібносерійного виробництва.
Bachelor’s dissertation: 86 pages, 20 figures, 30 tables, 16 references. The purpose of the work – optimize the technological processes of reproduction in metal copies, two works of art, according to the available non metallic originals. Research methodology – production of silicone and plaster molds with different variants of the foundry system; production of plaster-silica molds, their calcination and pouring at different temperatures; control of quality parameters of castings (surface roughness and the presence of casting defects). Results of the work and their novelty – theoretically and practically established the suitability of silicone molds for the manufacture of high-quality castings from low-melting (tin-lead) alloys; the parameters of technological processes of reproduction in metal copies of art products are investigated; made a series of high-quality art castings from tin-lead and copper alloy. The main indicators – as a result of work the optimum parameters of technological processes of manufacturing of art products are defined. A 0.099 kg Viking figure made of tin-lead alloy and 0.073 kg L63 brass was cast, as well as a 0.468 kg Celt statue made of L63 brass. The products do not have casting defects, the surface roughness does not exceed 12,5 microns and 6,3 microns, Areas of application – art and jewelry casting of unique products. Economic efficiency – UAH 214,137.4. Predictive assumptions about the development of the object of study – by analogy with the studied technological processes, the development of plans for the manufacture of similar size and complexity of cast art products in small scale production.

The columnar to equiaxed transition has been examined experimentally in lead-tin alloys. The effect of thermal conditions during solidification, melt superheat, and alloy composition on the transition have been considered. In directionally solidified alloys, the position at which the transition occured was dependent on the temperature distribution in the system, occuring when a specific low temperature gradient was reached at the advancing interface. Melt superheat did not influence the transition position. The alloy content affected the transition position, the transition occuring earlier at higher alloy contents. Adding particles to the melt did not change the position of the transition.
Applied Science, Faculty of
Materials Engineering, Department of
Graduate

An apparent inverse dependence of oxidation rate on temperature was discovered between approximately 270°C and 295°C using 60% tin-40% lead alloy as a result of a preliminary investigation carried out to determine the effect of temperature on the oxidation and drossing rates of stirred tin-lead alloy melts. This effect was found to be dependent on time and the composition of the alloy, and coincided with a considerable rise in drossing rate. Furthermore the oxidation rate of stirred 60% tin-40% lead alloy showed a very unusual increasing rate with time. Therefore a systematic study was carried out to determine the factors which control the oxidation and drossing rates of liquid tin-lead alloys, pure tin and pure lead at temperatures between approximately 200°C and 400°C. The results of the study are reported in two parts. In the first part the effects of time, temperature, the concentration of tin in the alloy, stirring rate and the effects of additions of up to 0.2% of copper, cadmium, zinc, aluminium, antimony silver and phosphorus on the weight gain and the weight of dross formed using stirred tin-lead alloys are reported. It was found that except for a phosphorus addition of 0.01% which reduces the weight gain of stirred 60% tin-40% lead alloy by at least 50%, the additions generally show only minor effects on the weight gain dependence of the alloy on temperature. The oxidation kinetics of stirred 60% tin-40% lead alloy have been interpreted using the Arrhenius equation. Drosses were examined and analysed using scanning electron microscopy, metallography, X-ray diffraction, X-ray photoelectron spectroscopy and atonic absorption spectrophotometry. In the second part of the study the effects of temperature and air pressure on the oxidation kinetics of static melts of 60% tin-40% lead alloy, pure tin and solid lead were determined using an electromicrobalance. Generally parabolic kinetics were observed indicating that the oxidation processes involved are diffusion controlled. It was also found that the oxidation gate of static melts of 60% tin-40% lead alloy at 270°C exceeds that at 295°C using an air pressure of 250 Pa although this effect is eliminated by reducing the air pressure to 50 Pa. Furthermore the oxidation rates of liquid 60% tin-40% lead alloy, pure tin and solid lead were in general higher using the lower air pressure of 50 Pa. The results obtained in this part of the study have also been inteipreted using the Arrhenius equation. Furthermore the oxide layers were examined and analysed using scanning electron microscopy and X-ray diffraction techniques. It appears that changes in the morphology of the oxide layer on liquid 60% tin-40% lead alloy may account for the observed changes in the oxidation rate of the alloy with, temperature and air pressure. A comparison of the oxidation rates of static and stirred melts of 60% tin-40% lead alloy show clearly that the oxidation rate of the stirred alloy is controlled by the additional surface area exposed as a result of drossing. Furthermore the nature of the oxide layer appears to have a significant effect on the drossing rate of the alloy. It was also shown by calculation that the observed time dependence of the fall in weight gain of stirred 60% tin-40% lead alloy with temperature could be explained in terms of the total surface area of the alloy exposed to the atmosphere.

For patients suffering bradycardia, i.e., too slow heart rhythm, the common treatment is having a pacemaker implanted. The pacemaker system consists of the pacemaker and a pacing lead. The pacing lead is connected to the pacemaker and at the other end there is a stimulation electrode. The most common conductor material is a cobalt-based super alloy (MP35N^® or 35N LT^®), with the main constituents Ni, Co, Cr and Mo. The pacemaker electrode is often made of a substrate material with a rough surface coating. The substrate materials are predominantly platinum/iridium alloy and titanium. The material choice is of great importance for the performance and stability during long-term service. Excellent corrosion resistance is required to minimize elution of metal ions in the human body.

In this thesis, the electrochemical behaviour and corrosion resistance of the Co-based alloys and Ta (as electrode substrate), in a phosphate buffer saline (PBS) solution with and without addition of H₂O₂, was investigated by means of potentiodynamic polarization, cyclic voltammetry, electrochemical impedance spectroscopy and simulated pacemaker pulsing. The metal release from the Co-based alloy during the passivation treatment and exposure in the synthetic biological media was measured by using inductive coupled plasma - atomic emission spectroscopy (ICP-AES). Moreover, surface composition was analyzed by using x-ray photoelectron spectroscopy.

The results show that the chemical passivation of Co-based alloy 35N LT^® increased the corrosion resistance and reduced Co release significantly, even in more hostile environment, i.e. PBS with addition of H₂O₂. The increased corrosion resistance is due to the Cr enrichment in the surface layer. The reduced Co release is due to a preferential dissolution of Co from the surface oxide layer during the chemical passivation. The electrochemical investigation of uncoated and rough TiN coated Ta show that uncoated Ta is not suitable electrode material due to formation of a highly resistive surface oxide film. Whereas the rough TiN coated Ta exhibits desirable electrochemical performance for pacemaker electrodes. The addition of H₂O₂ in the PBS has a large influence on the electrochemical behaviour of Ta, but the influence is small on the rough TiN coated Ta.

碩士
國立虎尾科技大學
機械設計工程研究所
102
In this project, in order to carry greater bearing loads and hence offer the possibility of reduction in overall bearing size for a given application.Use brominated, anodically oxidized, and pristine p-100 carbon fiber reinforced tin-lead alloy composites were fabricated by squeeze casting. The fibers were brominated by bromine vapor for 48 hours and then desorbed at 200℃ in air for 12 hours. The anodic oxidation treatment of fibers involved electrochemical etching in a dilute sodium hydroxide electrolyte for 3 min, or immersing in nitric acid for 72 hours. Finally, we accurately reproduce the composites containing surface-treated carbon fibers had higher tensile and interlaminar shear strength than the ones containing pristine carbon fibers. The composite containing brominated carbon fibers had better tensile strength than the other two surface treatments.

碩士
中國文化大學
應用化學研究所
87
The electronic industry is the single largest user of tin-lead solder materials. As such, it is important that this industry have a comprehensive understanding of solder properties and application issues in order to maximize solderability and wetting force. Solder point integrity can be ensured only once quality is assured. This thesis study employs two principal instruments, the wetting balance and x-ray fluorescence, and three methodologies, measurement system analysis, design of experiment, and the Taguchi methods, to determine interrelationships between solder, steam aging, penetration depth, and application dwell time and determine ideal process conditions. Doing so will ensure users achieve optimal balance between solder wetting force and solder layer thickness. Prior to do experiment, we assessed the repeatability and reproducibility of wetting balance and x-ray fluorescence instruments. The long method of measurement system analysis was employed to confirm a high level of stability and reliability of instruments used. The first stage of research employed an L827 Orthoganal Array to determine the number and conditions of tests needed to identify factors influencing solder performance factors. Factors identified include depth of solder penetration, application dwell time, and flux type. The second stage, using the Taguchi Methods, subjected the three factors of penetration depth, application dwell time, and flux type to the additional two factors of solder temperature and steam aging. The L827 Orthoganal Array was employed to identify the link between the two soldering properties of application dwell time and wetting force. Subsequently, we analyzed the applied solder based on a balance between the-larger-the-better bonding strength analysis and the-larger-the-better application thickness analysis to determine the optimal process conditions. This was determined in our research to be 245oC, using SM/NA [R Type] flux type, with steam aging of 0 hour, an application penetration depth of 2.5mm, and an application dwell time of 5 seconds. Such conditions ensured maximum wetting force with equivalent layer thickness.

碩士
國立成功大學
工程科學系專班
101
The casting skill has been developed for several thousand years. With the progress of time, the environment of application becomes more severe and hence the promotion requirements of material properties and mechanical strength increase. In a casting process, the temperature and concentration fields affect the microstructures of materials, which directly influence the mechanical and physical properties. The morphology of solidification microstructure is difficult to control in a casting process, while the grain size can be easily changed. The directional solidification and the growth of single crystal are the advanced casting techniques. In this experimental study of directional solidification, lead-tin alloy is used as the casting material and four experimental models with different heat temperatures, descending speeds of platform, water temperatures of copper chill are utilized to analyze their effects on the directional solidification. The microstructures are observed by using an optical microscope. The macro and micro structures are employed to investigate the influences of the four models on the control of preferred dendritic direction, the grain size, the constraint of dendritic growth, the temperature gradient and the growth rate. From the analysis results, it is expected to help the further grasp of the controlled mechanism of directional solidification.

碩士
國立虎尾科技大學
機械設計工程研究所
103
Abstract Tin-lead alloys with stable performance, embedded, low melting point, good fluidity, and corrosion resistance properties. Currently most often used in solder, bearings, aerospace and electronics industry, and if we can increase the bearing strength, it can reduce the overall dimensions of the bearing will be more cost and space. This experiment will carbon fiber soaking in 0.1mol/L of concentrated sodium hydroxide (NaOH) electrolytic liquid placed 3 minutes, in placed sulfuric acid nickel bath, by 8 volts and 10 amps plating 12-15 minutes, completed fiber surface processing, will carbon fiber into mold cavity, put mold temperature warming to 150 ℃, then will liquid solder heating to 300 ℃ pour mold, maintained in 150 ℃ and pressure range 30 to 50 MPa, immediately through piston in mold top Department put pressure on, in pressure maintained 10 minutes, While the mold is cooled to near room temperature. Test results found that after surface treatment of carbon fiber composite material and without surface treatment of carbon fiber composites, by contrast, after surface treatment has a high tensile strength and abrasion conditions, containing coated fiber composites are relatively good, but under sliding wear does not contain the coating of fiber composites are relatively good.

The life of lead-acid batteries is typically governed by corrosion of the positive grid. The grid experiences highly oxidising environments which, in turn, corrodes the grid material. However, the resulting corrosion layer is essential to create an electrically conductive bond between the grid and active material. Additionally, alloying elements are necessary to allow low-cost production techniques to be used. The selection of grid material is therefore a compromise between function, life and ease-of-manufacture. Tubular plate lead-acid batteries have historically used antimonial-lead alloys as the grid alloy. These alloys impart mechanical strength within a die-cast grid and provide a suitably conductive oxide within the corrosion layer. The use of tin in many lead alloy blends has resulted in a beneficial effect on the corrosion rate of these alloys. Tin-lead alloys are used in thin plate lead-acid batteries. However there is no published data on their use for grids of tubular plates in deep-cycling applications. A simple binary, low-tin lead alloy has been tested and found to exhibit a significantly lower corrosion rate during periods of heavy cycling when compared to a traditional low-antimony based alloy. However, it was shown that under severe over-charge conditions, the tin-lead alloy corroded at a significantly faster rate than that of an antimonial alloy. The lead-tin alloy performed well as a positive grid material throughout 500 cycles. No indications of premature capacity loss were observed and the ability of the alloy to be recharged was excellent. Electron microprobe analysis of sections of cycled positive plates showed the doping effect of tin within the corrosion layer of the grid material. This effect led to an increase in the conductivity of the layer, resulting in an increased ion-conductivity of the corrosion layer. The corrosion layer of each alloy type was found to be fine, densely packed and uniformly structured under cycling conditions, but it became more porous during periods of severe over-charge. The tin-based alloy was shown to produce a thinner corrosion layer at completion of 500 cycles when compared to that of the antimonial alloy. Further, the corrosion layer of the tin based alloy was found to be less cracked than that of the antimonial based alloy. Finally, this investigation could not identify any reasons why a tin-based grid alloy has not been identified for use in tubular plate deep-cycle batteries previously. The alloy was shown to perform well under both charge and discharge conditions and was not found to suffer premature capacity loss.
Thesis (M.Eng.Sc.) -- University of Adelaide, School of Chemical Engineering, 2015

碩士
國立虎尾科技大學
機械設計工程系碩士班
105
The results of this paper can make the bearing bear a bigger load,in practical applications can reduce the bearing size. Carbon fibers are made by casting to produce bromide and anodized for surface treatment. These two way and general carbon fibers are coated with nickel and copper,and the fibers are used to strengthen the tin-lead alloy composite. The fibers were brominated for 48 hours by bromine vapor and then desorbed at 200c in air for 12 hours；the other fibers involved electrochemical etching in a dilute sodium hydroxide electrolyte for 3 minutes. The experimental results show that the composites containing coated treated carbon fibres had higher tensile and shear strength than the ones containing coated pristine carbon fibres.Moreover,the composite with coated brominated carbon fibres had better tensile strength and shear strength than the surface treatment. In addition,the study of buckling analysis is mainly to explore the general metal-based composite materials and carbon fiber,tin-lead mixing ratio of the elongated hollow cylinder,the results of the deformation produced by a load compression are compared.

碩士
國立臺北科技大學
機電整合研究所
100
SnO2 is a very common materials used in gas sensor applications, caused by the change of resistance in a reducing atmosphere with the oxygen of the oxide surface adsorption reaction. Has been successfully applied to detect or identify a variety of toxic gases and combustion gases, such as CO, NO2, H2S, C2H6O2, CH4, etc. In this study, the use of vacuum die-casting will hypoeutectic, eutectic and hypereutectic molten tin-lead alloy molten metal cast into the nano template of anodic aluminum oxide(AAO), after curing of the liquid metal, the available array of tin-lead alloy nanowires after heat treatment oxidation array of tin-lead alloy nanowires, use wet etching to remove the template so that the wire bare copper thin films to complete device fabrication. Finally, on top of steamed copper thin films of metal semiconductor gas sensor production. The components of the composition, micro structure and nature of the detection while the Mapping、EDS、SEM、TEM、 XRD and DSC for analysis. The purpose of this study thin film sensor element as a control group, while the array of nanowire sensing element as a design group, the two groups of components in the same testing conditions, comparison of the sensitivity of the carbon monoxide response. Gas detection part is to design the measurement platform, the concentration of gas to be measured by MFC controls, signal measurement and signal data capture their writing LabView, finally confirmed with arrays of nanowire sensing element is much larger than than the surface area of thin film sensing element, therefore, the sensitivity increased substantially, the concentration of 500 ppm carbon monoxide atmosphere, nanowire array sensitivity of the sensing elements arranged in order SnO2(25.13%)＞Sn70%-Pb30%(17.83%)＞Sn63%-Pb37%(14.89%)＞Sn50%-Pb50%(14.02%).

碩士
國立成功大學
材料科學及工程學系
87
In electronic packaging lead-tin alloy is frequently used to joint electronic components. For the formation of solder joint, lead-tin alloy usually undergoes re-melting, fluid flow, and then solidification process. Therefore, the properties of lead-tin alloy solder joint and in turn the success of electronic packaging will be significantly affected by the reflow process. In this study, numerical analysis is employed to conduct solidification simulation for the reflow process. First a solid model for analysis is built based on the actual size and shape of the electronic component including the solder joint. Then the model has to be meshed for the subsequent numerical analysis. Since the components in electronic packaging, especially the solder joints, are usually very small and the element meshing has to be sufficiently fine for the analytical results to be meaningful, the element sizes are thus extremely small. The next step is to investigate all possible heat transfer mechanisms. All the relevant mechanisms have to be considered in the solidification model to calculate for the temperature distribution and variation of the lead-tin alloy solder joint during reflow process. A shrinkage criterion is also used to quantitatively predict the extent of shrinkage formation in the solder joint after the thermal history is calculated. In this study, heat transfer analysis is conducted for a particular electronic component to obtain the temperature distribution and variation of the lead-tin alloy as well as the whole electronic part during the reflow process. The calculated results are then compared to the cooling curves measured on designated locations of the actual part. As the solidification heat transfer analysis system proven to be reliable, it can then be used as a design tool to access the effects of design and operating conditions on the obtained properties of the lead-tin alloy solder joint after the reflow process.

The aim of the present thesis is to understand the phase transformation behavior of embedded alloy nanoparticles embedded in immiscible matrices. Embedded alloy inclusions have been dispersed in immiscible matrix via rapid solidification method. The present work deals with synthesis of embedded particles, evolution of microstructure, morphology and crystallographic orientation relation relationships among different phases, phase transformation and phase stability behavior of embedded alloy inclusions in different matrices. In the present investigation the systems chosen are Bi-Sn and Bi-Pb in Zn matrix and Cd-Sn in Al matrix. Chapter 1 gives the brief introduction of present work Chapter 2 gives a brief review of nanoscale materials, various synthesis techniques, microstructure evolution, solidification and melting theories. Chapter 3 discusses the processing and experimental techniques used for characterization of the different samples in the present work. Melt-spinning technique used to synthesize the rapidly solidified ribbons. The structural characterization is carried out using X-ray diffraction and transmission electron microscopy. Chapter 4 illustrates the size dependent solubility and phase transformation behavior of Sn-Cd alloy nanoparticles embedded in aluminum matrix. X-ray diffraction study shows the presence of fcc Al, bct Sn, hcp Cd solid solution and hcp Cd phases. Based on Zen’s law, the amount of Sn present Cd solid solution is estimated. Using overlapped sterograms, the orientational relationships among various phases are found. Microscopy studies reveal that majority of the alloy nano inclusions exhibit a cuboctahedral shape with 111 and 100 facets and they are bicrystalline. STEM-EDS analysis shows that both phases exhibit size dependent solubility behavior and for particles size smaller than 18 nm, single phase solid solution could only be observed. Calorimetric studies reveal a depression in eutectic melting point of bimetallic particles. In situ heating studies show that melting initiates at triple line junction corner and melt first grows into the interior of the Sn rich phase of the particle and then later the melt grows into the interior of the Cd phase of the particle. During cooling first Cd phase solidifies later Sn phase solidifies and on further cooling at low temperatures entire particle transforming into complete solid solution phase particle. Size dependent melting studies show that during heating smaller particles melted first, later bigger particles melted. During cooling first bigger particle solidified later smaller particles solidified. High resolution imaging indicates presence of steps across particle-matrix interface that may get annihilated during heating. During cooling, molten particles in the size range of 16-30 nm solidify as solid solution which for molten particles greater than 30 nm solidify as biphasic particle. Insitu heating studies indicates that for solid particles less than 15 nm get dissolved in the Al matrix at temperatures at around 135°C. Differential scanning calorimetry (DSC) studies show in the first heating cycle most of the particles melt with an onset of melting of at 166.8°C which is close to the bulk eutectic temperature of Sn-Cd alooy. The heating cycle reveals that the melting event is not sharp which can be understood from in-situ microscopy heating studies. In the second and the third cycles, the onset of melting observed at still lower temperatures 164.3°C and 158.5°C .The decrease in onset melting point in subsequent heating cycles is attributed to solid solution formation of all small particles whose size range below 30 nm during cooling. cooling cycles exhibit an undercooling of 90°C with respect to Cd liquidus temperature. Thermal cycling experiments using DSC were carried out by arresting the run at certain pre-determined temperatures during cooling and reheating the sample to observe the change in the melting peak position and area under the peak. The areas of these endothermic peaks give us an estimate of the fraction of the particles solidified upto the temperature when the cycling is reversed. Based on experimental observations, a thermodynamic model is developed, to understand the solubility behavior and to describe the eutectic melting transition of a binary Sn-Cd alloy particle embedded in Al matrix. Chapter 5 discusses the phase stability and phase transformation behavior of nanoscaled Bi-Sn alloys in Zn matrix. Bi-Sn alloys with eutectic composition embedded in Zn matrix using melt spinning technique. X-ray diffraction study shows the presence of rhombohedral Bi, pure BCT Sn and hcp Zn phases. In X-ray diffractogram, there are also other new peaks observed, whose peak positions (interplanar spacings) do not coincide either with rhombohedral Bi or bct Sn or hcp Zn. Assuming these new phase peaks belong to bct Sn rich solid solution(based on earlier work on Bi-Sn rapidly solidified metastable alloys) whole pattern fitting done on x-ray diffractogram using Lebail method. The new phase peaks indicated as bct M1(metastable phase1), bct M2(metastable phase2) phases. The amount of Bi present in M1, M2 solid solution is estimated using Zens law. Two sets of inclusions were found, one contains equilibrium bismuth and tin phases and the other set contains equilibrium bismuth and a metastable phase. In-situ TEM experiments suggest that as temperature increases bismuth diffuses into tin and becomes complete solid solution. Melting intiates along the matrix–particle interface leading to a core shell microstructure. During cooling the entire inclusion solidify as solid solution and decomposes at lower temperatures. High temperature XRD studies show that as temperature increases M1, M2 phases peaks merge with Sn phase peaks and Bi phase peak intensities slowly disappear and on further increasing temperature Sn solid solution phase peaks also disappear. During cooling diffraction studies show that first Sn solid solution phase peaks appear and later Bi phase peaks appear. But, the peaks belong to metstable phases not appeared while cooling. Chapter 6 presents morphology and phase transformation of nanoscaled bismuth-lead alloys with eutectic (Pb44.5-Bi55.5) and peritectic (Pb70-Bi30) compositions embedded in zinc matrix. using melt spinning technique. In alloy1[ Zn-2at%(Pb44.5-Bi55.5)] inclusions were found to be phase separated into two parts one is rhombohedral Bi and the other is hcp Pb7Bi3 phase. X-ray diffraction study shows the presence of rhombohedral Bi, hcp Pb7Bi3 and hcp Zn phases in Zn-2at%(Pb44.5-Bi55.5) melt spun sample. The morphology and orientation relationships among various phases have been found. In-situ microscpy heating studies show that melt initially spreads along the matrix–particle interface leading to a core-shell microstructure. And in the core of the core-sell particles, first Bi phase melts later Pb7Bi3 phase will melt and during cooling the whole particle solidify as biphase particle with large undercooling. In-situ heating studies carried out to study the size dependent melting and solidification behavior of biphase particles. During heating smaller particles melt melt first later bigger particle will melt. In contrast, while cooling smaller particles solidifies first, later bigger particles will solidify. Detailed high temperature x-ray diffraction studies indicate there increases first Bi phase peaks disappear later Pb7Bi3 phase peaks disappear and during cooling first Pb7Bi3 phase peaks appear and later Bi phase peaks appear. In alloy2[ Zn-2at%(Pb70-Bi30)] inclusions were found to be single phase particles. X-ray diffraction study shows the presence of hcp Pb7Bi3 and hcp Zn phases in Zn-2at%(Pb70-Bi30) melt spun sample. The crystallographic orientation relationship between hcp Pb7Bi3 and hcp Zn phases. In-situ microscpy heating studies show that melting initiates across the matrix–particle interface grows gradually into the interior of the particle. Three phase equilibrium at peritectic reaction temperature is not observed during insitu heating TEM studies. Size dependent melting point depression of single phase particles is not observed from in-situ heating studies. Detailed high temperature x-ray diffraction studies show that while heating the Pb7Bi3 phase peak intensities start decreasing after 170°C and become zero at 234°C. And during cooling Pb7Bi3 phase peaks starts appearing at 200°C and on further cooling the Pb7Bi3 phase peak intensities increase upto 150°C, below this temperature peak intensities remain constant.

博士
國立成功大學
材料科學及工程學系碩博士班
93
The thermal physical properties of the Sn-9Zn-xX (X = Ag, Cu) lead-free solder alloy systems are examined in this study. The effects of alloy composition and cooling rate on the liquidus temperature, solidus temperature, pasty ranges, latent heat release modes, fusion heats and coefficient of thermal expansion were investigated. 　　A Computer Aided-Cooling Curve Analysis (CA-CCA) technique was used to determine the pasty ranges and latent heat release modes for the alloys. The solidification model proposed by Hwang was used to quantity the results. The Differential scanning calorimetry was also used to measure the liquidus temperature and solidus temperature of alloys. The fusion heat of the alloys was also calculated. The morphology of alloys and intermetallic compounds were observed with Scanning electron microscope and Electron probe microanalyzer. Energy dispersive spectrometer and Wave dispersive spectrometer were used to analyze the chemical compositions and elemental dispersion of intermetallic compounds. The CTE of Sn-Zn-xAg alloys is measured by using a dilatometer with a heating rate of 5 �aC/min from 40 �aC to 120 �aC. 　　The experimental results show that as the silver content of the Sn-9Zn-xAg alloy increases, the liquidus temperature rises and the pasty range broadens. However, when the silver content exceeds 1.5%, a second peak can be observed from the heating and cooling curves. As long as the silver content is below 0.5 wt%, silver has little effect on the microstructure because it is basically the eutectic Sn-9Zn and the fs-T relationship is nearly a vertical line. However, as the silver content exceeds 1.5 wt%, the formation of the Ag-Zn intermetallic compounds becomes obvious. This causes the alloy composition to deviate from the eutectic and to lean towards the tin-rich side of the Sn-Zn phase diagram. This in turn causes the proportion of the primary tin phase to increase and that of the zinc-tin eutectic phase to decrease. This is reflected on the plot of the fs-T relationship by two distinct vertical regions. One corresponds to the primary tin phase and the other to the eutectic phase. As the silver content further increases, the effects of intermetallic compound formation become even more obvious. As an alternative to CA-CCA, Huang’s model can be used to obtain a quantitative fs-T function. As the silver content increases, the primary solid fraction for Huang’s model increases. As the cooling rate increases, the primary solid fraction and the nonlinearity factors ne and np decrease. The CTE is increased with increasing temperature. When the temperature reaches 90 ℃, the increase becomes less obvious. Furthermore, CTE increases linearly with increasing silver content. As the silver contents are over 1.5%, the values of CTE are greater than the conventional Sn-37Pb alloy. Based on the above observations, silver content should not exceed a maximum of 1.5% in order to develop a lead free solder with proper thermo-physical properties. 　　The results also show that as the copper content of the Sn-9Zn-xCu alloy increases, the liquidus temperature rises and the pasty range broadens. However, when the copper content is 0.6 wt%, the eutectic like situation can be observed from the heating and cooling curves. As long as the copper content is below 0.1 wt%, copper has little effect on the microstructure, which is basically the eutectic Sn-9Zn and the fs-T relationship is nearly a vertical line. However, as the copper content exceeds 0.6 wt%, the formation of Cu-Zn intermetallic compounds becomes obvious. This is reflected on the plot of the fs-T relationship by two distinct vertical regions. One corresponds to the primary tin phase and the other to the eutectic phase. As the copper content further increases, the effects of intermetallic compound formation become even more obvious. As an alternative to CA-CCA, Huang’s model can be used to obtain a quantitative fs-T function. Sn-9Zn-xAg and Sn-9Zn-xCu ternary alloy systems have similar thermal physical behavior. The fusion heat of three Sn-Zn based lead free solder alloy experimental measured in this study are all higher than lead-tin solder alloy.

碩士
國立成功大學
工程科學系碩博士班
101
Solidification processes play an important role in the morphology control of microstructures. The morphology of solidification microstructure is difficult to master in a casting process. Accordingly, in the thesis, four experimental models of different heating styles, contact surfaces of copper chill, environment temperatures and casting methods are used to study their effects on the directionally solidified lead-tin alloys. The heating style could affect the grain size. The copper chill supply an axial temperature gradient, which could make columnar grains grow along the opposite directional of the heat flow. The columnar growth could decrease the lateral grain boundaries and elevate the material life span. In addition, the microstructure observation through an optical microscope incorporated with the macrostructures and temperature-measured data is used to investigate the influences of the four experimental models on the constraint of dendrite growth, the equiaxed zone at the bottom of the casting, the competition zone of preferred growth directions for the columnar grains and the grain size. Furthermore, based on the classification of the microstructure morphology, the differences among the castings are analyzed.

L’objet de la présente étude est le développement, l’application et la diffusion de la technologie associée à divers types d’alliages de cuivre, en particulier l’alliage du plomb-bronze, en Grèce ancienne, dans ses colonies, ainsi qu’en Étrurie. Le plomb-bronze est un mélange de diverses proportions d’étain, de cuivre et de plomb. Le consensus général chez les archéométallurgistes est que le plomb-bronze n’était pas communément utilisé en Grèce avant la période hellénistique; par conséquent, cet alliage a reçu très peu d’attention dans les documents d’archéologie. Cependant, les analyses métallographiques ont prouvé que les objets composés de plomb ajouté au bronze ont connu une distribution étendue. Ces analyses ont aussi permis de différencier la composition des alliages utilisés dans la fabrication de divers types de bronzes, une preuve tangible que les métallurgistes faisaient la distinction entre les propriétés du bronze d’étain et celles du plomb-bronze. La connaissance de leurs différentes caractéristiques de travail permettait aux travailleurs du bronze de choisir, dans bien des cas, l’alliage approprié pour une utilisation particulière. L’influence des pratiques métallurgiques du Proche-Orient a produit des variations tant dans les formes artistiques que dans les compositions des alliages de bronze grecs durant les périodes géométrique tardive et orientalisante. L’utilisation du plomb-bronze dans des types particuliers d’objets coulés montre une tendance à la hausse à partir de la période orientalisante, culminant dans la période hellénistique tardive, lorsque le bronze à teneur élevée en plomb est devenu un alliage commun. La présente étude analyse les données métallographiques de la catégorie des objets coulés en bronze et en plomb-bronze. Elle démontre que, bien que l’utilisation du plomb-bronze n’était pas aussi commune que celle du bronze d’étain, il s’agissait néanmoins d’un mélange important d’anciennes pratiques métallurgiques. Les ères couvertes sont comprises entre les périodes géométrique et hellénistique.
The subject of this study is the development, application and diffusion of the technology of various types of copper alloys, particularly that of leaded bronze, in ancient Greece, its colonies, and in Etruria. Leaded bronze is a mixture of tin, copper and lead in various proportions. The general consensus among archaeometallurgists is that leaded bronze was not commonly used in Greece until the Hellenistic period, and thus this alloy has not received very much attention in archaeological literature. However, metallographic analyses demonstrate that objects composed of leaded bronze had a wide distribution. The analyses also show differentiation in the composition of alloys that were used in the manufacture of various types of bronzes, a tangible indication that metalworkers distinguished between the properties of both tin bronze and leaded bronze. The knowledge of their different working characteristics is what enabled a bronzeworker to choose, in many cases, the appropriate alloy for a specific application. The influence of Near Eastern metallurgical practices produced variations in both the artistic forms as well as alloy compositions of Greek bronzes during the Late Geometric and Orientalizing periods. The use of leaded bronze for particular types of cast objects shows an increasing tendency from the Orientalizing period onwards, culminating in the late Hellenistic period when high-lead bronze became a common alloy. This study analyzes the metallographic data of specific categories of bronze and leaded bronze cast objects, and it will demonstrate that although the use of leaded bronze was not as prevalent as that of tin bronze, it was nevertheless a significant adjunct of ancient metallurgical practices. The periods surveyed range from the Geometric to the Hellenistic periods.

This study investigates the reliability of SnPb and SnAg solder joints in semiconductor packages subjected to thermal cycling. More specifically, solder joint crack growth and life are experimentally measured, and FEM models are run to explain the test results. Ultimately a life-prediction model is proposed for both SnPb and SnAg solder joint packages. Motorola 357-plastic ball grid array packages on printed wiring boards were thermal cycled with the following test parameters: SnPb and SnAg solders, three post-process conditions (aged, aircooled and quenched), four package layouts on the printed circuit boards (singledense, single-sparse, double-alternating, and double-dense), three accelerated thermal cycling protocols (0°C to 100°C, -40°C to 125°C, and -55°C to 125°C), and tests run at Motorola and the University of Texas. At predetermined thermal cycles, packages were removed from the environmental chambers, dyepenetrated, packages removed to expose the solder joints, and optical images taken. Images were processed to measure crack area, shape, orientation and length to show crack growth. Selected joints were sectioned and polished to investigate microstructure and failure modes. Selected boards were connected to an ANATECH event detector to monitor life from joint failures. FEM crack initiation and propagation models were developed to better understand failure mechanisms. Major experimental results are: 1) SnPb joints have about 50% faster crack growth rates than SnAg joints, subsequently SnPb joints have half the life of SnAg joints, 2) air-cooled and quenched packages had similar failure characteristics, but aged SnPb joints had lower life and aged SnAg joints had significantly longer life than the comparable nonaged joints, 3) double-dense package layout significantly decreased life (by 75%) over the other package layouts, which were similar to each other, 4) the test results at the two locations (UT and Motorola) were similar for SnPb solder joints, but significantly different for SnAg solder joints, and 5) the largest cracks occurred at the corners of joints just under the die edge. Major FEM simulation results are: 1) the crack initiation life of SnAg joints is approximately 100% longer than SnPb joints, 2) shear load is a major cause of crack growth, but the contribution of tensile load increases as the cracks grow, 3) primary cracks at the board interface appear to reduce the propagation rate of the primary crack on the package interface, 4) secondary cracks are suppressed when compressive stresses prevent voids from nucleating, 5) the double-dense configuration shows no PWB warping due to symmetry, and its stresses are larger than for the other package layouts, and (6) the stresses and strains for single-dense, single-sparse, and double-alternating package layouts are similar because the stresses/strains are dominated by local effects due to the CTE mismatch between the die and board. Based upon the experimental results and FEM simulations, a lifeprediction model based upon a severity metric was proposed. The metric estimates damage to the solder joints and links material properties and parameters associated with package layout and thermal test conditions to the time-dependent creep, time-independent plastic deformation, and a time-dependent and geometric effective stress of the solder. The severity metric predicted life very well for most of the data tested and was more accurate than the industry-standard life-prediction models for SnPb solder joints.