A method for preparing oriented structural coating by reverse cooling

Abstract

A method for preparing a directional structure coating by reverse cooling, the steps of which are: (1) preparing a self-dissolving Ni-based alloy powder as a preset coating for a protected workpiece, with a coating thickness of 0.1-1.0mm; and then using induction The remelting method performs secondary remelting treatment on the coating, and the remelting temperature is controlled at about 100~150°C lower than the melting point of the alloy; (2) After remelting, the coating is naturally cooled to 100~250°C lower than the remelting heating temperature , or when it is about 200~300°C lower than the melting point of the coating alloy; cooling water is passed through the coating surface, so that the coating is reversely cooled from the surface to the substrate, and the coating structure is reversely solidified, forming Fine-grain oriented structure coating; (3) Adjust the induction heating temperature to 300~450°C, and then heat the coating at a low temperature again, that is, the cooled coating is subjected to rapid tempering treatment; (4) The above-mentioned prepared The workpiece is buried in sand and cooled slowly.

Description

technical field [0001] The invention relates to the field of surface engineering, in particular to the technology of reversely cooling the coating surface to prepare an oriented structure coating. Background technique [0002] Metal-based coatings have experienced three generations of development, from the first generation of single-component coatings, the second generation of binary composite coatings to the currently widely used multi-component composite coatings and multi-layer coatings. The development of industry has made a great contribution. With the development of science and technology, in order to control and improve the coating quality and obtain coatings with better performance, people usually add various reinforcements to the coating to obtain high-performance composite coatings. However, the addition of this second phase has problems with its fit and compliance with the substrate coating material, which often leads to microscopic interface defects in the coati...

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Problems solved by technology

[3] Guo Linshan. Fine control of out-of-plane orientation of high-temperature superconducting films and research on large-scale crystal growth [D]. Shanghai Jiao Tong University, 2017.), however, these technologies can only be used to prepare thin films at present, and directional solidification technology is applied at home and abroad For the preparation of thick coatings on the surface, there are few reports at home and abroad on the research of making the coating have a directional structure. The structural anisotropy of the coating is controlled, and then the coating performance is controlled by the direction, so as to improve the toughness of the coating in an oriented manner. The tribological behavior of chemical and coating has great engineering value (Yang Xiaotian, Wang Pengchun, Li Xia, Lu Yang, Xiao Rongzhen. Microstructure and performance evolution characteristics of Ni-based alloy coating prepared by composite[J]. Rare Metal Materials and Engineering, 2017, 46 (3):693-698.)

([1] Wang Pengchun, Lu Yang, Yang Xiaotian, Xiao Rongzhen, Yang Xiaowei. The effect of forced cooling on the microstructure of induction remelting Ni60 alloy coating [J]. Chinese Journal of Nonferrous Metals, 2016,26(2):375-382.[ 2] Lu Yang, Gong Lu, Yang Xiaotian, Xiao Rongzhen, Duan Junling, Fu Xiaoyue. Effect of Surface Insulation on Solidification Behavior of Directional Solidification Ni60 Alloy Coating [J]. China Surface Engineering, 2018, 31(4):130- 139.) However, this cooling method is difficult to achieve forced cooling from the direction of the substrate for workpieces with special structures. For example, for cylindrical workpieces, it is impossible to apply cooling from the direction of the substrate

Moreover, even for workpieces that can be cooled from the direction of the substrate, it is difficult to precisely control the cooling rate of the coating alloy due to the influence of substrate thickness, thermal conductivity, etc.

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