Authors: M. Shunmuga Priyan; P. Hariharan
Addresses: Department of Manufacturing Engineering, Anna University, Chennai-25, Tamil Nadu, India ' Department of Manufacturing Engineering, Anna University, Chennai-25, Tamil Nadu, India
Abstract: Thermally sprayed coatings that are based on FeSiNiCr-related alloy powders are widely used to improve properties such as the surface hardness, the wear resistance and the corrosion resistance of a variety of coated metal substrate materials. For the current study, the FeSiNiCr-containing coating formulations were thermally sprayed onto a grey cast iron substrate by the high velocity oxy fuel (HVOF) method under controlled conditions. The microstructure and micro abrasive wear performance of both the uncoated substrates and the coated substrates were characterised by optical microscopy as well as by scanning electron microscope (SEM). In addition, X-ray diffraction (XRD) and thermogravimentric analyses (TGA) were undertaken in the partial characterisation of the coating. The densely layered coating had porosity levels that were below 1.5% and a high surface hardness, of the order of 920 HV0.1. The coating exhibited excellent wear resistance when subjected to the ball-cratering test method. The wear rate of coating was significantly less than the wear rate of the substrate. Low coefficients of friction of hard coating on the substrate were recorded. The wear performance of the coating was nearly 80% better than that of the substrate, with a 0.05 N load, even under severe three body abrasive conditions. A tribometer was used to assess the wear testing to evaluate the change in the coefficient of friction and the wear rate with respect to the change in time.
Keywords: micro abrasive wear test; microhardness; FeSiNiCr alloys; HVOF method; high velocity oxy fuel; grey cast iron; spray coatings; thermal spraying; microstructure; coefficient of friction; wear rate.
International Journal of Surface Science and Engineering, 2013 Vol.7 No.3, pp.250 - 268
Received: 20 Jun 2012
Accepted: 20 Mar 2013
Published online: 16 Sep 2013 *