Abstract: Three similar varieties of pure Ti hydride-dehydried (HDH) powders were tested for the understanding of the variables that have an influence on the compaction process of Ti powders. The study shows that small differences in the characteristics of the powders lead to very different behaviours in the compaction stage. Compressibility curves, friction with the die walls and ejection forces are discussed in this study. The results are compared with a commercial iron powder as a reference to complete the discussion, as well as to show the enhancements and modifications that should be performed in Ti powders to design an optimized powder suitable for being pressed in an industrial process.
Abstract: A brief background to compaction equations and their application to titanium powder is presented. The behavior and mechanisms of densification in selected titanium powders is critically analyzed by means of a comprehensive inter-model comparison of existing compaction equations. The results are discussed in terms of the comparative evaluation of cold uniaxial compaction tests of sponge Ti, CP TiH2, CP Grade 2 Ti, and TiH2-SS316L nanocomposite powder samples, which were conducted at applied compaction pressures of up to 1250 MPa.
Abstract: The colloid-chemistry control of metallic powders in aqueous slurries is proposed as a way to produce spherical granules of fine titanium particles able to be processed by powder metallurgy (PM) techniques. Significant improvement of sintering behavior is achieved, leading to high dense parts at reduced sintering temperature and time. Consequently the control of grain growth during sintering was achieved, as well as the oxygen content. This approach can be extended to other strategies for Ti design, such as the homogeneous dispersion of second phases for further control of grain size and modification of properties.
Cites background from "Study of Compaction and Ejection of..."
...Results in this work demonstrate that spherical powders can be successfully processed by cold pressing through granules shaped in a previous colloidal step, achieving green density values even higher than those obtained by coarser and irregular-shaped powders [3,16,17]....
Abstract: The effects of die wall lubricants on the cold compaction of titanium hydride powder are studied. Three commonly-used die wall powder metallurgy lubricants – zinc stearate, Acrawax® C dispersion and Mirror Glaze® – are compared. The influence of each lubricant on the cold compaction behaviour of titanium hydride powder was assessed with respect to the green density and strength, green compact ejection force, and the occurrence of green compact cracking. In addition, green compacts were sintered under vacuum at various sintering temperatures in order to determine the effect of the lubricants on oxygen content, phase compositions, microstructures and hardness of the sintered components. The results indicate that there is an immediate improvement in the cold compaction process when lubrication is used. The results further indicate that the lubricity of the lubricants is similar and most of the monitored variables are insensitive to the die wall lubricant used, the microstructures of the sintered components included. However, the use of Acrawax® dispersion resulted in more instances of green compact cracking, while zinc stearate tended to increase the oxygen content of sintered specimens due to the tentative decomposition of zinc oxide, a residual of the high temperature decomposition of zinc stearate.
Abstract: This paper reports on an attempt to independently evaluate the validity and applicability of a new compaction equation recently presented by Gerdemann and Jablonski [Metallurgical and Materials Transactions A, 42 (2011) 1325–1333] using experimental data. Furthermore, the rationality of Gerdemann and Jablonski’s interpretation of the equation parameters is examined. The results are discussed in terms of the comparative evaluation of four different titanium powders (sponge Ti, CP TiH2, Grade 2 CP Ti, and TiH2-SS316L nanocomposite blend prepared by high energy milling) cold pressed in die to compaction pressures of up to 1300 MPa.
Abstract: Changing the material parameters such as powder characteristics and additives affects the final properties of an iron–carbon alloy. This study investigated the influences of three typical material parameters, iron particle size, graphite addition, and powder lubricant addition, on the density and mechanical properties of an iron–carbon alloy formed via powder compaction and sintering. Each material parameter was designed with five levels, and all of the powder mixtures were compacted under 500 MPa and sintered at 1120 °C for 30 min. The microstructure of the samples was observed for the green part and sintered part. Through the tensile test, yield strength, ultimate tensile strength, and elongation were measured. The tensile fracture surface was also examined to understand the changes in mechanical properties according to the parameters. The correlations between mechanical properties and material parameters were characterized by the mapping functions, and a sensitivity analysis was carried out to investigate which parameter had the larger influence on the mechanical properties. The results showed that graphite addition has the greatest influence on the mechanical properties due to the microstructural changes from hypoeutectoid structure to hypereutectoid structure. Further, a regression model was developed to describe the mechanical response of the iron–carbon alloy depending on the material conditions.
Abstract: Designed to support the need of engineering, management, and other professionals for information on titanium by providing an overview of the major topics, this book provides a concise summary of the most useful information required to understand titanium and its alloys The author provides a review of the significant features of the metallurgy and application of titanium and its alloys All technical aspects of the use of titanium are covered, with sufficient metals property data for most users Because of its unique density, corrosion resistance, and relative strength advantages over competing materials such as aluminum, steels, and superalloys, titanium has found a niche in many industries Much of this use has occurred through military research, and subsequent applications in aircraft, of gas turbine engines, although more recent use features replacement joints, golf clubs, and bicycles Contents include: A primer on titanium and its alloys, Introduction to selection of titanium alloys, Understanding titanium's metallurgy and mill products, Forging and forming, Castings, Powder metallurgy, Heat treating, Joining technology and practice, Machining, Cleaning and finishing, Structure/processing/property relationships, Corrosion resistance, Advanced alloys and future directions, Appendices: Summary table of titanium alloys, Titanium alloy datasheets, Cross-reference to titanium alloys, Listing of selected specification and standardization organizations, Selected manufacturers, suppliers, services, Corrosion data, Machining data
TL;DR: The focus of this paper is aircraft and aircraft engines but the broader focus is on the role of materials in creating lightweight structures, and there are examples used that are relevant to automotive applications once they are adjusted for cost.
Abstract: This paper examines the progress in aircraft and aircraft engines from the standpoint of the role that better materials and processing has played. Such progress includes the relatively recent transformation of the aircraft industry from purely performance driven products to products that are driven by customer value. It is demonstrated that advances in materials and processing technology and understanding has enabled much of the progress that has been made since the inception of manned, heavier than air flight. The recent constraints of cost, as determined by customer value, have changed the way new materials are introduced and these trends appear to be the new paradigm for the aircraft and aircraft engine industry. While the focus of this paper is aircraft and aircraft engines, the broader focus is on the role of materials in creating lightweight structures. There are examples used in this paper that are relevant to automotive applications once they are adjusted for cost. This matter is briefly discussed at the end of the paper.
Abstract: This comprehensive book provides state-of-the-art scientific and technical information in a clear format and consistent structure making it suitable for formal course work or self-instruction. T ...
TL;DR: An electrochemical method for the direct reduction of solid TiO2 is reported, in which the oxygen is ionized, dissolved in a molten salt and discharged at the anode, leaving pure titanium at the cathode.
Abstract: Many reactive metals are difficult to prepare in pure form without complicated and expensive procedures Although titanium has many desirable properties (it is light, strong and corrosion-resistant), its use has been restricted because of its high processing cost In the current pyrometallurgical process--the Kroll process--the titanium minerals rutile and ilmenite are carbochlorinated to remove oxygen, iron and other impurities, producing a TiCl4 vapour This is then reduced to titanium metal by magnesium metal; the by-product MgCl2 is removed by vacuum distillation The prediction that this process would be replaced by an electrochemical route has not been fulfilled; attempts involving the electro-deposition of titanium from ionic solutions have been hampered by difficulties in eliminating the redox cycling of multivalent titanium ions and in handling very reactive dendritic products Here we report an electrochemical method for the direct reduction of solid TiO2, in which the oxygen is ionized, dissolved in a molten salt and discharged at the anode, leaving pure titanium at the cathode The simplicity and rapidity of this process compared to conventional routes should result in reduced production costs and the approach should be applicable to a wide range of metal oxides
Abstract: Titanium alloys, because of their excellent mechanical, physical and biological performance, are finding ever-increasing application in biomedical devices. This paper provides an overview of titanium alloy use for medical devices, their current status, future opportunities and obstacles for expanded application. The article is divided into three main sections, the first discussing recent efforts focused on commercial purity titanium. This is followed by considering effects of chemistry, grain size and α/β morphologies on mechanical properties of α + β alloys. Finally, the third section reviews the status of metastable β alloys specifically designed for biomedical applications emphasizing their aging behavior and its effects on mechanical properties.