https://bura.brunel.ac.uk/bitstream/2438/13101/1/FullText.pdf

Cold spraying - A materials perspective

Friction stir welding/processing of metals and alloys: A comprehensive review on microstructural evolution

Microstructural evolution and mechanical properties of dissimilar Al–Cu joints produced by friction stir welding

Friction stir welding of titanium alloys: A review

Gas tungsten arc welding assisted hybrid friction stir welding of dissimilar materials Al6061-T6 aluminum alloy and STS304 stainless steel

Important issues in developing hydroxyapatite (HAp)- and titanium (Ti)-based composite biomaterials for orthopedic or dental devices include the dissociation of HAp during fabrication and its influences in the microstructure and biocompatibility of the final composite. During the densification by sintering of HAp/Ti composites, Ti reacts with OH freed from HAp to form TiO2 thus dissociated HAp into Ca3(PO4)2, CaO, CaTiO3, TiP, and so forth. To inhibit this reaction, composites were fabricated with Ti and 30, 50, and 70 vol % β-tricalcium phosphate (β-TCP) instead of HAp by spark plasma sintering at 1200°C. It has been observed that after sintering at 1200°C, Ti also reacted with TCP, but unlike HAp/Ti composites, the final TCP/Ti composites contained significant amounts of unreacted TCP and Ti phases. The initial 70 vol % TCP/Ti composite showed compressive strength of 388.5 MPa, Young's modulus of 3.23 GPa, and Vickers hardness of 361.9 HV after sintering. The in vitro cytotoxicity and proliferation of osteoblast cells on the composites surfaces showed that the addition of a higher amount of TCP with Ti was beneficial by increasing cell viability, cell–composite attachment and proliferation. Osteopontin and collagen type II protein expression from osteoblasts cultured onto the 70% TCP–Ti composite was also higher than other composites and pure Ti. In vivo study verified that within 3 months of implantation in an animal body, 70% TCP–Ti had an excellent bone–implant interface compared with a pure Ti metal implant. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2013.

Microstructure and biocompatibility of composite biomaterials fabricated from titanium and tricalcium phosphate by spark plasma sintering.

This study aims to investigate the effect of the orientation of Gr powder and the volume fraction of Cu and Gr on the thermal conductivity (TC) and coefficient of thermal expansion (CTE) of Cu-Gr composites. Coarsening Gr flake (CGF) powder was coated with Cu through electroless plating (EP) method and was then sintered using pulsed current activated sintering. The present study confirmed that the presence of Cu oxide layer formed between Cu layer and CGF powder via electroless plating process and how it decomposes during the pulsed current activated sintering process. The anisotropy Gr has different characteristics depending on the bonding direction. In order to control the bonding direction of outstanding thermal properties of Gr, a stacking-pressing process was carried out, and the thermal conductivity was measured. The TC and CTE of Cu-Gr composites were measured in the longitudinal and transverse direction according to difference of Cu-Gr volume fraction, and were compared with theoretical value.

Effect of volume fraction and unidirectional orientation controlled graphite on thermal properties of graphite/copper composites

Mechanical properties and microstructural evolution of WC-binderless and WC-Co hard materials by the heat treatment process

In this study, the manufacture of a large thickness Cu coating layer as sputtering target material via a cold spray coating process was undertaken. The microstructure and properties of the Cu layer as the sputtering target material (before and after the annealing heat treatment) were evaluated, compared, and analyzed. To evaluate the purity, density, grain size and uniformity, microstructure, and properties of the Cu-coated layer as a sputtering target, X-ray diffraction, ICP analysis, SEM, EBSD, porosity analysis, and Vickers hardness tests were performed. The result of the observation of the layer’s purity and microstructure showed that a purity level (99.47%) similar to that of the early powder 2N5 was maintained and that the manufacture of a cold spray deposited, ∼20 mm thick Cu coating material for the sputtering target was performed successfully. As a result of the EBSD mapping, the average grain size near the interface and around the center measured 1.48 μm and 1.49 μm; the grains were small and non-uniform compared with the 1.91 μm size near the surface. Note, however, that the recrystallization and grain growth (caused by annealing) increased the grain size to 1.82 μm (near the interface), 1.83 μm (near the center), and 1.87 μm (near the surface) and improved the level of uniformity. Moreover, through post heat treatment, the overall porosity declined (0.44 % porosity/400 °C/h heat treatment), and the grain texture became uniform. The possibility of controlling the microstructure as a large thickness sputtering target by conducting an annealing heat treatment was also confirmed. Nonetheless, the differences in the porosity and hardness associated with the coating thickness changes were partially maintained. Based on the aforementioned findings, this study suggests that by using cold spray deposition, Cu coating layers with large thicknesses can be applied as a sputtering target.

Ik-Hyun Oh

Papers

Gas tungsten arc welding assisted hybrid friction stir welding of dissimilar materials Al6061-T6 aluminum alloy and STS304 stainless steel

Microstructure and biocompatibility of composite biomaterials fabricated from titanium and tricalcium phosphate by spark plasma sintering.

Effect of volume fraction and unidirectional orientation controlled graphite on thermal properties of graphite/copper composites

Mechanical properties and microstructural evolution of WC-binderless and WC-Co hard materials by the heat treatment process

Manufacture and properties of cold spray deposited large thickness Cu coating material for sputtering target