Titanium and titanium alloys are widely used in biomedical devices and components, especially as hard tissue replacements as well as in cardiac and cardiovascular applications, because of their desirable properties, such as relatively low modulus, good fatigue strength, formability, machinability, corrosion resistance, and biocompatibility. However, titanium and its alloys cannot meet all of the clinical requirements. Therefore, in order to improve the biological, chemical, and mechanical properties, surface modification is often performed. This article reviews the various surface modification technologies pertaining to titanium and titanium alloys including mechanical treatment, thermal spraying, sol–gel, chemical and electrochemical treatment, and ion implantation from the perspective of biomedical engineering. Recent work has shown that the wear resistance, corrosion resistance, and biological properties of titanium and titanium alloys can be improved selectively using the appropriate surface treatment techniques while the desirable bulk attributes of the materials are retained. The proper surface treatment expands the use of titanium and titanium alloys in the biomedical fields. Some of the recent applications are also discussed in this paper.

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Surface modification of titanium, titanium alloys, and related materials for biomedical applications

Recent advances in friction-stir welding : Process, weldment structure and properties

Discrete particle simulation of particulate systems: A review of major applications and findings

Consolidation phenomena in laser and powder-bed based layered manufacturing

This review article aims to provide an updated and comprehensive description of the development of the Electric Current Activated/assisted Sintering technique (ECAS) for the obtainment of dense materials including nanostructured ones. The use of ECAS for pure sintering purposes, when starting from already synthesized powders promoters, and to obtain the desired material by simultaneously performing synthesis and consolidation in one-step is reviewed. Specifically, more than a thousand papers published on this subject during the past decades are taken into account. The experimental procedures, formation mechanisms, characteristics, and functionality of a wide spectrum of dense materials fabricated by ECAS are presented. The influence of the most important operating parameters (i.e. current intensity, temperature, processing time, etc.) on product characteristics and process dynamics is reviewed for a large family of materials including ceramics, intermetallics, metal–ceramic and ceramic–ceramic composites. In this review, systems where synthesis and densification stages occur simultaneously, i.e. a fully dense product is formed immediately after reaction completion, as well as those ones for which a satisfactory densification degree is reached only by maintaining the application of the electric current once the full reaction conversion is obtained, are identified. In addition, emphasis is given to the obtainment of nanostructured dense materials due to their rapid progress and wide applications. Specifically, the effect of mechanical activation by ball milling of starting powders on ECAS process dynamics and product characteristics (i.e. density and microstructure) is analysed. The emerging theme from the large majority of the reviewed investigations is the comparison of ECAS over conventional methods including pressureless sintering, hot pressing, and others. Theoretical analysis pertaining to such technique is also proposed following the last results obtained on this topic.

Consolidation/synthesis of materials by electric current activated/assisted sintering

http://www.jwri.osaka-u.ac.jp/~dpt9/2017.pdf

Tensile properties and fracture locations of friction-stir-welded joints of 2017-T351 aluminum alloy

In order to determine the effect of the carbon content and the transformation on the mechanical properties and microstructures of the FSW carbon steel joints, three types of carbon steels with different carbon contents (IF steel, S12C, S35C) were friction stir welded under various welding conditions. Compared with IF steel, the microstructures and mechanical properties of the carbon steel joints are significantly affected by the welding conditions. The strength of the S12C steel joints increases with the increasing welding speed (decreasing the heat input), while the strength of the S35C steel joints shows a peak near 200 mm/min. This can be explained by the relationship between the peak temperature and the A 1 and A 3 points. When friction stir welding is performed in the ferrite–austenite two-phase region, the microstructure is refined and the highest strength is then achieved.

Friction stir welding of carbon steels

Prospecting the optimal tool design for welding steels, the effect of the tool shape on the mechanical properties and microstructures of 5-mm thick welded aluminum plates was investigated. The simplest shape (column without threads), the ordinary shape (column with threads) and the triangular prism shape probes were used to weld three types of aluminum alloys. For 1050-H24 whose deformation resistance is very low, a columnar tool without threads produces weld with the best mechanical properties; for 6061-T6 whose deformation resistance is relatively low, the tool shape does not significantly affect the microstructures and mechanical properties. For 5083-O whose deformation resistance is relatively high, the weldablity is significantly affected by the rotation speed. For a low rotation speed (600 rpm), the tool shape does not significantly affect the microstructures and mechanical properties of the joints.

Effect of tool shape on mechanical properties and microstructure of friction stir welded aluminum alloys

Friction stir welding of a high carbon steel

A critical review is given of the present state of knowledge and future perspectives in high-temperature contact angle measurement. Experimental results obtained by the different versions of the sessile drop method and by various procedures are given in order to illustrate the two main sources of scatter in wettability data, the first being related to the quality of the substrates and the second to control of the furnace atmosphere.

Kiyoshi Nogi

Papers

Tensile properties and fracture locations of friction-stir-welded joints of 2017-T351 aluminum alloy

Friction stir welding of carbon steels

Effect of tool shape on mechanical properties and microstructure of friction stir welded aluminum alloys

Friction stir welding of a high carbon steel

Measurement of contact angle and work of adhesion at high temperature