Phase composition, microstructure and microhardness of electroless nickel composite coating co-deposited with SiC on cast aluminium LM24 alloy substrate

Abstract

Rajendran, R. (2013). Phase composition, microstructure and microhardness of electroless nickel composite coating co-deposited with SiC on cast aluminium LM24 alloy substrate. Surface and Coatings Technology, 235,[755][756][757][758][759][760][761][762][763] 600048, IndiaAbstract: Electroless Ni-P (EN) and composite Ni-P-SiC (ENC) coatings were developed on cast aluminium alloy substrate, LM24. The coating phase composition, microstructure and microhardness were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM) and microhardness tester, respectively, on as-plated and heat-treated specimens. The original microstructure of the Ni-P matrix is not affected by the inclusion of the hard particles SiC. No formation of Ni-Si phase was observed up to 500°C of heat treatment. The microhardness is increased on incorporation of SiC in Ni-P matrix. The hardening mechanism is the formation of intermetallic phase Ni3P on annealing at elevated temperature.

Micro-scale wear characteristics of electroless Ni–P/SiC composite coating under two different sliding conditions

“…1 shows the coating cross-section of the sample which is uniform and follows the same contour of the substrate. From our previously reported study [20], the typical cauliflower microstructure of the coating was observed. The inclusion of second phase particles (SiC) does not affect its original microstructure of the nickel matrix.…”

Insight of the interface of electroless Ni–P/SiC composite coating on aluminium alloy, LM24

“…Electroless nickel composite coating (Ni-P/SiC) characteristics such as phase composition, microstructure and properties like microhardness, surface roughness and wear characteristics have been reported and discussed in our previous studies [3,4]. In the present investigation, the zincating layer at the interface and any changes arising at the vicinity of the interface are analysed systematically.…”

“…All the specimens underwent pre-treatment for cleaning prior to the coating. The cleaning process and parameters were referred from Franco et al [3] shown in Table 1. Extreme care was taken to transfer the specimens to the in-lined cleaning solutions as quickly as possible.…”

“…Prior to the plating, the particles were introduced to the bath (proprietary medium phosphorus electroless nickel base solution, NiKlad ELV 808MX, MacDermid) and stirred using magnetic stirrer for 30 min for homogenous suspension. Plating process and parameters are given in Table 2 [3]. Stirring rate was chosen after several trials to minimise sedimentation at the bottom and to obtain optimal distribution of the particles (stirring speed at level 5 in the magnetic stirrer, model HB502, Bibby Sterilin Ltd., UK make).…”

“…Metal coatings by electrochemical techniques are promising and widely used owing to their economy and better output. The deposition of nickel with phosphorus [2] reinforced with hard particles like silicon carbide, SiC, using electroless method is a versatile composite coating that can transform the inferior Al alloy substrate [3,4]. Other types of particles like Al2O3 [5] and CeO2 [6] have also been used in nickel based coatings.…”