Research On Structure And Wear Resistance Of Ti N-TiB₂/Fe Metal Ceramic Coating Prepared By Reaction Nitrogen Arc Cladding

Constant improvement of agricultural mechanization and automation requires increasingly higher of performances of agricultural tools. However, tool wear results in reduced whole performance, heavier working resistance and increased fuel consumption; frequent replacement delays the farming season and increases the cost in actual production. Thus, it is of great significance to produce agricultural tools with low cost and high service life so as to catch up with fast development of modern agricultural mechanization.With nitrogen as the protective gas and reactant gas, this topic adopts reaction nitrogen arc cladding technology and WSME-630 argon arc welder to realize in-situ synthesis of Ti N-Ti B2/Fe cermet composite coating on Q235 matrix which is pre-coated with Ti powder, BN powder and Ni60 powder so as to improve abrasive resistance of agricultural tools and extend the service life, studies feature, phase, hardness and abrasive resistance of the coating by KYKY-2800 B scanning electron microscope, D/max-2500 rotating anode X-ray diffractometer, S-4800 cold field emission scanning electron microscope energy dispersive spectrometer, MH-6 microhardness tester and HRS-2M reciprocating friction wear tester, optimizes technological parameters and analyzes formation mechanism and wear-resistance mechanism of Ti N-Ti B2/Fe coating.Additionally, this topic studies influences of different contents of binding phase Ni60 upon coating molding and microscopic structure, confirms that the coating is flat and evenly formed without open defects when the binding phase proportion is about 40% and the abrasive resistance is comparatively good. It is observed by electron microscope that the coating can be divided into coating zone, binding zone and base zone. A transition belt with good metallurgical bonding is formed in the binding zone between the coating and the base.Moreover, single factor experiment is carried out to study influences of nitrogen flow, cladding current and cladding velocity upon structure, hardness and friction coefficient of the coating; the results show that too low nitrogen flow leads to powder oxygen and too high nitrogen flow leads to spatters which are bad for coating formation. However, cladding current and cladding velocity mainly influence the scalding temperature. The higher the temperature is, the larger the bath is; the base will be smelted and boiling, plenty of Fe elements will infiltrate into the coating and hard particles will be diluted so that coating performance cannot be improved. Nevertheless, too low temperature will result in slow in-situ synthesis or failure so that Ti N and Ti B2 cannot be generated. Technological parameters of coating with favorable comprehensive performance: nitrogen flow 10L/min, cladding current 160 A, cladding velocity 2.5mm/s.The optimal technological parameters acquired in this research are adopted to generate a Ti N-Ti B2/Fe cermet composite coating; the maximum hardness is HV0.5980 and the abrasive resistance is about 3.7 times of the base’s. When measured against abrasive resistance of common 65 Mn steel agricultural tools, this coating cutter is feasible in the production of agricultural tools.