Investigating the Ability of Coating the SiC by APS and HVOF Processes through the Nickel-Phosphorus Cladding on the Primary Powder : Pejman Zamani Moghadam; Zia Valefi; Masoud Mirjani : Free Download, Borrow, and Streaming : Internet Archive (2024)

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Pejman Zamani Moghadam; Zia Valefi; Masoud Mirjani

In this research, silicon carbide (SiC) powder with a particle size of
30 to 45 micrometers and an irregular morphology was used for coating in
an electroless nickel bath. The effect of particle surface roughening
parameters in an acidic solution and electroless process time on
uniformity and thickness of Ni-P coating on the SiC particles was
investigated. SiC(Ni)-70vol.%Co blended powder was coated on simple
carbon steel substrates by high-velocity oxy-fuel (HVOF) and atmospheric
plasma spraying (APS) processes. The composite powder was obtained from
the mechanical blending of cobalt powder with coated silicon carbide
SiC(Ni) powder. The microstructure and morphology of powder particles
and corresponding coatings were investigated by scanning electron
microscopy (SEM). The results showed that the surface preparation of SiC
powder by roughening the particles with HF/NaF solution and electroless
time of 5 minutes led to the formation of a continuous and uniform Ni-P
coating with a thickness of 1-3 micrometers on the SiC particles.
Electroless nickel coating during thermal spraying by HVOF protected SiC
particles against decomposition and oxidation and as a carrier led to
the placement and distribution of SiC in SiC(Ni)-Co composite coating.
In the APS process, due to the very high temperature of the plasma jet
and thermal decomposition, SiC particles was insignificantly contributed
to the coating microstructure. The micro-hardness of two mentioned
coatings was measured as 570±40 and 460±30 HV0.3, respectively, and this
difference was due to the effect of the significant distribution of SiC
in the HVOF coating.