No abstract

No abstract

Titanium and its alloys have various excellent properties, such as good corrosion resistance and high specific strength. Yet the poor tribological properties of these materials have so far precluded their application to sliding parts under severe wear conditions.Laser alloying is an effective process for improving wear resistance. This study was conducted to investigate the wear properties of Ti/TiC surface composite layer formed by laser alloying process of CP-Ti using graphite powder. Wear testing of the composite layer was carried out using a ball-on-flat type reciprocating wear tester.A hardened steel ball for bearing use and an Al 2 O 3 ball were used as counterface materials for the wear testing. The tests with the steel ball revealed preferential wearing of the hardened steel, with no observable scarring the Ti/TiC composite. In the tests with the Al 2 O 3 ball, the wear scar on the Ti/TiC composite layer was deeper than the wear scar on a non-laser irradiated substrate.

Laser alloying using a carbon steel substrate pre-coated powder mixture of pure titanium and graphite was carried out to form an FeTiC composite surface layer for improving wear resistance. The microstructure of the composite layer was studied in detail using OM, SEM, XRD and STEM to reveal the effect of the laser alloying conditions on the distribution of carbides. Coarse particles (15 µm) and submicron particles of TiC were observed. TiC particles were distributed in a lath martensite matrix, and the area fraction of TiC was about 8 to 25%. The area fraction and size of TiC depended on the laser scanning speed. Under the condition of a high scanning speed, a composite layer with a high area fraction and a coarser size of TiC was obtained. These composite layers exhibit high hardness and superior wear resistance compared with a laser transformation hardened area of the same substrate.

No abstract