Tribological Properties of Ni-P Electroless Coatings on Low-Carbon Steel Substrates Using an Environmentally Friendly Pretreatment

Abstract

This study deposits Ni-P alloy films coatings onto low carbon steel substrates using an electroless process. The coating's morphology and properties, including the hardness, polarization and frictional behavior, are analyzed. A conventional pretreatment that uses roughening and activation steps ensures better adhesion between the Ni-P plated layer and the substrate and renders the substrates catalytic. This study reports an environmentally friendly pretreatment for the substrates: physical sandblasting (using emery powder particles) and oxygen plasma etching. XRD analysis shows that the diffraction pattern for the Ni-P alloy exhibits a wider peak, which indicates that there is an amorphous phase. SEM micrographs after electroless Ni-P plating that uses plasma etching show that the surface is more even and fairly smooth, which indicates good Ni-P film characteristics. The experimental results show that a plasma etching pretreatment for coating with Ni-P film increases the hardness and corrosion resistance and reduces the coefficient of friction.

Common Defect Analysis for Large Section Special Steel Forging

“…10(b) showed that there was mainly Cr segregation. As known to all, Cr promotes ferrite formation [9,10], so the Cr enrichment in local area was the key cause of the δ ferrite. On account of the large size and grain boundary characteristic, the effect of δ ferrite to prevent crack propagation is very small, so the δ ferrite is the the favorable place for crack initiation and propagation.…”