Comparing Between Effect of Plasma and Heat Treatment and on Wear behavior of Ni-B-CNT Electro less Coating on AISI 4340

Abstract

The aims of the work are to study the hardness,resistance of wear of plus plasma-nitriding and heat treatment of coatings with electroless Ni-B-CNT. Various concentration of CNT range , 0 g/L ,0.35 g/L and 0.7 g/L in (Ni-B-CNT) composite isdeposit on 4340 steel in electroless immersion. Following the procedure of plating, every samples were plasma-nitriding in atmosphere consist of 50%N2–50% H2at(400°C)for(4h) were compared with those of annealed one.. The wear behavior and friction of a composite that plating were valued by pin on disk technique used load applied of (10N). The electroless Ni–B –CNTcoatings are prepared by using nickel chloride as source for nickel in alkaline bath, borohydride act as reducing agent and used Multi walled carbon nanotubes(MWCNT).The formulasare characterized withFESEM, microhardness ,XRDandsurface roughness measurements. Surfaces ofworn arealsostudiedwithEDS spectroscopy and FESEM.Results of that microhardness are show that the largerhardness of 1250 HV is obtained for (Ni-B 0.35g/L CNT) plasma-nitriding formula whereasthe greatest hardness of 1010 HV isbecome for sample of (Ni-B 0.35g/L CNT) heat treated. As a results, enhance the concentration of CNTs caused structure of coated Ni-B conversionfrom amorphous to crystalline .The present of CNT not just decrement the size of grain toplasma-nitriding and heat treated formulas but also prevent extreme heat production through procedure of test wear and the friction coefficient is decreasedthrough that test. Furthermore, image of surface worn of Ni-B 0.35g/L CNT plasma-nitriding sample detect the smoothest wear tracethe highest wear resistance and not apparent cracks among all the samples was achieved. whilst, in formula of Ni-B-0.7g/L CNT, and agglomeration that occur createroughness in addition tobig particles with weakly joinedin matrix of Ni in ultimately led to increase in the wear rate.