Method for preparing coating containing Ti (C and N) with melamine as carbon and nitrogen precursor

Abstract

The invention discloses a method for preparing a coating containing Ti (C and N) with melamine as a carbon and nitrogen precursor and relates to the technical field of ceramic / metal composite coating preparation. The method includes the following steps of 1, preparation of the graphite phase g-C3N4; 2, substrate pretreatment; 3, coating layer pre-forming and drying; 4, plasma cladding; and 5, formation of finished products. The low-cost organic compound containing carbon and nitrogen, namely, melamine serves as the carbon and nitrogen precursor, and carbon nitride powder is prepared in advance and serves as a solid carbon and nitrogen source for in-situ synthesis of the metal ceramic composite coating containing Ti (C and N). The powdery solid nitrogen source is stable in structure, convenient to weigh and accurate in weighing. The quantity of the solid nitrogen source can directly affect the phase composition and the coating structure and performance of end products obtained through the in-situ reaction after fusion covering, so that the mass fraction of the solid nitrogen source is changed to accurately adjust and control the organization structure and performance of the coating so as to meet the design requirements, and the novel method is also provided for surface strengthening of agricultural machinery materials or tools and molds.

Description

technical field [0001] The invention relates to the technical field of preparation of ceramic / metal composite coatings, in particular to a method for preparing titanium carbonitride-containing reinforced iron-nickel-based composite coatings on iron substrates by using an organic compound-melamine as a carbon-nitrogen precursor. Background technique [0002] The main methods for preparing Ti(C,N)-based cermets include powder metallurgy, such as self-propagating high-temperature synthesis and sintering; followed by deposition methods such as chemical vapor deposition, physical vapor deposition, plasma deposition, etc.; and reaction casting. And in-situ synthesis technology such as laser or plasma cladding in-situ synthesis technology. Among them, the powder metallurgy method uses TiC, TiN or Ti(C,N) powder as the hard phase, Ni, Mo, Co, etc. as the binder phase, which is pressed into shape after ball milling, and sintered in a vacuum or controlled atmosphere. Isostatic pressi...

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Problems solved by technology

In the method of preparing Ti(C,N), TiC, TiN coating, such as laser cladding-laser gas nitriding method to prepare Ti(C,N)-TiN composite cladding layer, nitrogen arc cladding TiCN / Fe Coating, spark deposition reaction synthesis of TiN reinforced metal matrix composite coating, etc., these methods are basically based on N 2 Gas is the nitrogen source, and a high-energy heat source is used to in-situ synthesize Ti(C,N) composite coatings on the surface of the substrate. During the in-situ reaction process, gas-solid or gas-liquid reactions mainly occur, and the nitrogen source is in contact with Ti. Insufficient, resulting in low nitrogen content in the nascent phase formed by the reaction, although it can be increased by increasing N 2 flow method to increase the content of nitrogen in the cladding coating, but accompanied by N 2 When the flow rate increases within a certain range, the energy density of the heat source increases during the cladding process (during nitrogen arc cladding, the energy beam density and enthalpy of the nitrogen arc are higher than those of the argon arc), resulting in an increase in the temperature of the molten pool, which is likely to cause coating The components are severely burned, and even the base material is excessively melted, and N is required during the cladding process. 2 The purity is very high, the density of nitrogen is lower than that of air at normal temperature, and the density of nitrogen after heating is even smaller, so the protection of nitrogen to the molten pool is significantly reduced during the cladding process, and it is also inevitably mixed with air volume Into the protective air flow, so it will produce other harmful phases, which will reduce the performance of the coating

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