Thermal spraying has different classifications according to different standards:
(1) According to the different properties of spraying materials, thermal spraying can be divided into metal spraying, ceramic spraying, plastic spraying, etc.
(2) According to the shape of the spraying material, thermal spraying can be divided into powder spraying, wire spraying, bar spraying, etc.
(3) According to the nature of the spraying heat source, thermal spraying can be divided into gas combustion flame spraying, arc spraying, plasma spraying, laser spraying, etc.
Table 1 Comparison of parameters of several thermal spraying technologies
spray method
Flame temperature °C
particle velocity
Bond strengthporosity
porosity
Spraying efficiency
relative cost
m/s
N/mm2
%
Kg/h
flame spray
3000
30-180
8-12
10-30
2-6
1
explosive spray
3000
800-1200
>70
0.1-1
1
4
high speed flame spray
2500-3100
500
70-110
<10
1-5
2-3
Arc spray
4000-6000
250
15-25
10-20
10-25
2
plasma spray
20000-30000
200-800
50-80
<10
2-10
4
⒉ Characteristics of thermal spraying
The equipment is light and can be constructed on site. The process is flexible and the operation procedures are few. Can be repaired quickly and reduce processing time. It has strong adaptability and is generally not limited by the size of the workpiece and the site. , The coating thickness can be controlled. In addition to spray welding, the heating temperature of the base material is low, the deformation of the workpiece is small, and the metallographic structure and performance changes are also small. It is suitable for parts of various base materials and can be prepared on almost all solid material surfaces. Coatings and functional coatings.
From the analysis of the principle and process of thermal spraying technology, thermal spraying technology has the following characteristics.
① Due to the wide temperature range of the heat source, the coating materials that can be sprayed include almost all solid-state engineering materials, such as metals, alloys, ceramics, cermets, plastics and their composites. Surfaces with functions (such as abrasion resistance, corrosion resistance, high temperature resistance, oxidation resistance, insulation, thermal insulation, biocompatibility, infrared absorption, etc.).
②The heating degree of the surface of the substrate during the spraying process is small and can be controlled, so it can be sprayed on various materials (such as metal, ceramics, glass, cloth, paper, plastic, etc.), and the structure and properties of the substrate are almost There is no influence, and the deformation of the workpiece is also small.
③The equipment is simple and the operation is flexible. It can not only spray a large area of large components, but also spray the designated parts; it can be sprayed in the factory or in the outdoor site.
④The spraying operation has fewer procedures, shorter construction time, high efficiency and more economical. With the improvement of thermal spraying application requirements and the expansion of the field, especially the progress of spraying technology itself, such as the increasingly high-energy and sophisticated spraying equipment, coating The variety of layer materials has gradually increased, and the performance has gradually improved. Thermal spraying technology has achieved rapid development in the past ten years. Not only has the application field been greatly expanded, but the technology has developed from the early preparation of general protective coatings to the preparation of various functional coatings Layer; from the repair of a single workpiece to the manufacture of a large number of products; from a single coating preparation to include product failure analysis, surface pretreatment, coating material and equipment development, selection, coating system design and coating post-processing It has become a very active subject in the field of material surface science, and has gradually formed independent material processing technologies such as casting, forging, welding and heat treatment in modern industry. It has become an industrial sector to save valuable materials and save Energy, improving product quality, extending product life, reducing costs, and improving work efficiency are important technological means, which have become more and more widely used in various fields of the national economy.
