Structure and hardness of titanium surfaces carburized by pulsed laser melting with graphite addition

Abstract

To cite this version:Bruno Courant, Jean-Jacques Hantzpergue, Ludovic Avril, Stéphane Benayoun. Structure and hardness of titanium surfaces carburized by pulsed laser melting with graphite addition. Titanium foils coated with graphite films 20 m thick were irradiated by means of a pulsed Nd-YAG in order to harden this metal by surface melting and alloying. The relationships between irradiation parameters, microstructure and hardness of the synthesized composite coatings were determined. Four relevant parameters were defined as governing the irradiation processes. The parametric working field of the laser source was investigated next to its periphery. The influences of the relevant irradiation parameters on the microstructure and hardness of the melted zone were deduced from the metallographic analyses and Vickers micro-indentation tests of the cross sections of this composite zone. Such a zone was constituted always with hard titanium carbide and ductile metallic titanium, some times with the presence of lubricating graphite inclusions. The main advantage of such a surface treatment of titanium is to synthesize, under clearly defined irradiation conditions, a self-lubricating composite coating that resists abrasive or adhesive wear.

Surface Modification Techniques for Biomedical Grade of Titanium Alloys: Oxidation, Carburization and Ion Implantation Processes

“…Many researchers reported that the carbide layer enables to increase hardness, wear resistance and corrosion resistance to titanium and its alloy (Kim et al, 2003). Sintered solid titanium carbide is a very important non-oxide ceramics that widely used in the fields of wear resistance tools and materials due to its high melting point (3170 o C), low density, high hardness (2500 ~3000HV), superior chemical and thermal stability, and outstanding wear resistance (Courant et al, 2005). Apart from sintering, titanium carbide layer can be created by other surface modification methods, such as plasma carburizing process, thermal carburization or high-temperature synthesis, carburization by laser melting, gas-solid reaction or gas carburization and sol-gel process , Yin et al, 2005, Cochepin et al, 2007, Luo et al, 2011.…”

“…This process involved heating of specimen through continuous or pulse wave laser irradiation, rapid melting, intermixing or diffusion of carbon particle, and rapid solidification of the pre-deposited alloying elements on substrate to form an alloyed zone or carburized layer. Investigations on laser carburizing technique were extended from steel to -Titanium (Fouilland et al, 1997), commercial pure titanium (Courant et al, 2005) , and biomedical grade titanium (Sampedro et al, 2011). Laser melting carburization produces thick coating ranged between one and several hundred micrometers depending on the irradiation conditions.…”

“…The effects of these variables are investigated in terms of changes to the hardness, compositions, heat affected zone, pores, cracks and microstructure of the carburized zone. For instance, a group of researchers investigated the effect of processing time on the TiC microstructure formation on titanium alloy using Nd-YAG laser (Courant et al, 2005). They observed that the time ratio has a significant effect on the carburized microstructure.…”

Direct Laser Fabrication process with coaxial powder projection of 316L steel. Geometrical characteristics and microstructure characterization of wall structures

“…Direct Laser Fabrication (DLF) is a new rapid manufacturing process based on laser cladding and derived from welding, microwelding and laser technologies [1][2][3][4]. A power laser beam heats powder grains delivered from a coaxial nozzle system.…”

Characterisation of titanium–titanium boride composites processed by powder metallurgy techniques

“…However, titanium boride (TiB) is well suited for use as reinforcement due to the absence of any intermediate phase between Ti and TiB [8][9][10]. Moreover, TiB reinforcement has certain desirable characteristics such as high elastic modulus, good thermal stability at high temperature and a density nearly equal to that of titanium [11].…”