Ti̇tani̇um plasma paste bori̇di̇ng

Plasma paste boriding using boron products (borax, boric acid, boron carbide) can easily be done. The resources that used in plasma boriding (BCl3, BF3, B2H6) are corrosive and expensive; moreover the resources which are used at the process of solid boriding are inported from abroad. Due to these facts plasma paste boriding is becoming more appealing. During this process, the use of boron resources, borax and boric acid which are found in high amounts in our country, would allow boron consumption and the use of a beneficial area of boron source. In this study, plasma paste boriding was performed for Ti (grade2) and Ti6Al4V (grade 5) alloy using borax paste at temperature of 700, 750 and 800 ̊C for duration of 3, 5 and 7 h in the gas mixture of 30% Ar - 70% H2 at working pressure of 5 mbar. After plasma paste boriding, the samples were cut in cross-section, ground by 240 to 1000 grit emerypaper and polished using alumina suspension with size 0,01 µm. The surface of borided samples were characterized using optical microscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD) microhardness and surface profilometer. Optical microscopy and SEM examination revealed that TiB2 phase on the outermost layer has flat morphology, whereas TiB phase has whisker morphology. As a result of XRD analysis, showed that, TiB and TiB2 phases formed on the surface of both titanium as well as α-Ti phase from the substrate. While boriding processing time and tempetature increased, it was observed that the layer thickness also increases, and the value of the layer thickness has been reached form 1,6 µm to 5,4 µm. Microhardness of boride layers was determined by Knoop method, and the hardness values have been determined as of 2200 - 2380 HK0,025. The surface roughness of pure titanium and titanium alloy was measured by using perthometer M2 device. Growth kinetics of titanium boride layer as investigated energy was determined for the treated temperature and time. Key Words: Plasma boriding paste, Titanium, Titanium Alloy, Titanium boride, Diffusion kinetics.