This study investigates the use of cold gas spraying (CGS) for depositing braze filler coatings. In the experiments, pure Cu layers were sprayed onto Mg alloy substrates, which were then joined to AlSi steel by contact reaction brazing in a vacuum furnace. The bonding temperature influenced the dissolution of Cu as well as the eutectic reaction between the coating and substrate. The thickness of the brazed seam was found to be 300 μm although the initial thickness of the Cu layer was just 50 μm. The shear strength of the joint peaked at 37 MPa, corresponding to a brazing temperature of 530 °C. Intermetallic phases and interfacial defects of various types were responsible for the low strength of the joints.

In this paper, nano-structured TiO 2 coatings have been successfully deposited onto titanium alloy substrates by atmospheric plasma spraying technology using optimized plasma parameters. A chemical treatment method was employed to induce bioactivity on the TiO 2 surface. The bioactivity of as-sprayed and chemical treated TiO 2 coatings were evaluated by investigating the formation of apatite on their surface after they were soaked in simulated body fluids (SBF) for a period of time. Microstructure and the phase composition of the as-sprayed coating and apatite were analyzed by Field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and energy-dispersive X-ray spectrometry (EDS). The results obtained indicate that as-sprayed TiO 2 coating consists of rutile, anatase and suboxide such as Ti 3 O 5 . The surface of nano-TiO 2 coating is covered by nano particles of about 50nm in size. The bonding strength of TiO 2 coating with Ti alloy substrate is as high as 40 MPa. The corrosion resistance performance of nano-coating in SBF is better than that of Ti-6Al-4V alloy. The surface of as-sprayed TiO 2 coating can not induce bone-like apatite formation. Chemical treatment, such as acid and alkali, can improve bioactivity of TiO 2 coating surface.

This paper describes some of the problems solved in the development of a mold-making process in which the molds are coated using a 2mm wire arc-spraying system. A water solution release agent has been chosen to meet industry standards and requirements. The composition of backup materials was chosen based on compression strength testing. The material selected has high ultimate compression strength and high thermal conductivity and can be readily incorporated in the mold-making process.