The purpose of this paper is to characterize carbide coatings obtained by thermo reactive diffusion (TRD) method on AISI 52100 and 440C bearing steels, which are extensively used…
Abstract
Purpose
The purpose of this paper is to characterize carbide coatings obtained by thermo reactive diffusion (TRD) method on AISI 52100 and 440C bearing steels, which are extensively used in industry, and to study wear behaviour of coated steels at elevated temperatures.
Design/methodology/approach
For coatings of vanadium and titanium carbides, TRD treatment is performed on AISI 52100 and 440C steels using pack method at 950°C for 3 h. Carbide coatings are characterized using X‐ray diffraction (XRD). The Daimler‐Benz Rockwell‐C adhesion test and micro‐Knoop indenter is used to assess the adhesion and hardness of the carbide layers, respectively. Ball‐on‐disc arrangement is used for determination of tribological properties of carbide‐coated steels. Friction and wear tests are carried out against Si3N4 ball at elevated temperatures up to 600°C under 5 N load, for sliding speed of 0.3 m/s.
Findings
The presence of carbides formed on AISI 52100 (Ti6C3.75 and VC0.88 phases) and on AISI 440C (Ti6C3.75, VC0.88 and minor Cr23C6 and Cr7C3 phases) is confirmed by XRD analysis. Hardness values of titanium and vanadium carbides on the 52100 and 440C steels are about 2,175‐2,464 and 2,128‐2,433 HK0.05, respectively. Friction experiments show that this type of coating is more effective than the substrates in regards to achieving lower friction up to 300°C. Above this temperature, the effect of substrate is more dominant on the friction coefficient. Scanning electron microscopy and energy‐dispersive X‐ray analysis results show the presence of the compact oxide layers at elevated temperatures as a result of increased sintering and oxidation of the wear debris.
Research limitations/implications
This paper deals with only characterization of vanadium and titanium carbide coatings and high temperature wear properties of the coated steels.
Practical implications
Carbide coatings obtained by TRD method are satisfactory in terms of high temperature tribological applications in comparison with those produced vapor deposition processes, which are expensive and complicated equipment.
Originality/value
There is no literature about high temperature wear and friction behaviour of TRD carbide‐coated 52100 and 440C steels. In this study, there are new results on high temperature wear of TRD carbide‐coated steels.