The Effect Of Additives On Formation Process Of Fe Based Alloy Composite Coating

Coating on metal surface coating is an important means to improve the surfaceproperties of metals. This paper adopts the vacuum fusion sintering process, coatingof Fe based alloy coating on45#steel matrixes, using the method of reactionthermodynamics and thermal analysis kinetics analysis for the reaction mechanism ofcoatings with different content of additives, measurement and analysis the phasecomposition, phase composition and micro hardness measurement of the coating withdifferent additives content, using OM, SEM, EDS, XRD, microhardness tester andother equipment, the results show that:(1) The Gibbs free energy of the possible chemical reactions in the coating by thechemical reaction thermodynamics calculations show that: In the process of vacuumfusion sintering, the strongest trend is that WC occur chemistry reaction with Crwhich in the matrix. This means the Cr in the matrix could hasten WC’s dissolution.(2) Using differential scanning calorimetry analyzer simulation Fe based alloycoating in vacuum fusion sintering process, and using the Freeman-Carroll methodanalysis to the DSC curve, researching WC’s decomposition reaction kinetics duringvacuum fusion sintering process, calculating the apparent activation energy and thereaction orders of the reaction, the results show that: Adding CeO2will increase WCactivation energy of the decomposition reaction, and the highest apparent activationenergy of WC’s decomposition reaction is the coating with0.4percent of CeO2; thedifferent addition of WC itself have an effect on the decomposition activation energy.It’s the most difficult to WC’s decompose, when WC’s content is30percent.(3) Preparing Fe based alloy coating by vacuum fusion sintering process,analyzing the microstructure and the phase composition of the coating, the resultsindicate that: The addition of CeO2can change the morphology and distribution ofcoating, make crystals small and uniform, enhance the compactness of coating. Thecoating gets the most tight microstructure, the smallest grain and the best combinationbetween coating and substrate when the addition of CeO2is0.4percent; properaddition of WC can effectively reduce the defect in the coating, refine microstructureof coating, and enhance the bonding strength of hard phase and coating. The coatinggains the densest and best organization when WC content is20percent.(4) Analyzing the hardness of Fe base alloy coating, the results show that: Theaddition of CeO2improves the surface hardness of the coating. The surface hardnessof the coating is best when the content of CeO2is0.4percent; the proper amount ofWC increases the surface hardness of coating. The surface hardness of the coating isbest when the content of WC is30percent.