Application of laser assisted cold spraying process for materials deposition

The Laser-Assisted Cold Spraying (LACS) process is a hybrid technique that uses laser and cold spray mechanism to deposit solid powders on metal substrates. For bonding to occur, the particle velocities must be supersonic. The supersonic effects can be achieved by passing a highly compressed Nitrogen gas (~30 bars) through de Laval supersonic nozzle. LACS is a surface coating technique that is desirable in rapid prototyping and manufacturing, particularly for biomedical applications. Current world research reveals that the capability of the LACS regarding the enhancement of surface properties of coating titanium alloys with hydroxyapatite will be essential for fabricating scaffolds for bone implants using Laser Engineered Net Shaping (LENS) technique. In this chapter, coatings of composite powders made of titanium and hydroxyapatite deposited on Ti-6Al-4V substrate by LACS technology are presented. These coatings were successfully characterised by means of X-Ray Diffraction (XRD) and optical microscopy for their phases, composition, and microstructure, respectively. The results of the produced LACS coatings compare well with those obtained with traditional thermal spray and cold spray techniques, respectively. In addition, the XRD results were found to be similar to the precursor powders, which indicated that no phase transformation occurred to HAP. Coatings comprising of other crystalline phases of HAP are less bio-integrable and fail quicker within the human body fluids environments.