1 Sample preparation and test method
1.1 The coating sample preparation test uses the valve core ball material 40Cr13 martensitic stainless steel as the spraying base material, with a size of 60mm 15mm; Its chemical composition (calculated by mass fraction, the same below) is 0.38% C, 0.62% Si, 0.80% Mn, 0.050% P, 0.030% S, 12.87% Cr. According to the test, the valve core ball has been quenched and tempered at low temperature, its structure is tempered martensite, and its hardness is 512~545HV0.2. The plasma spraying feed materials are nano-Al2O3-13% TiO2 and WC-12% Co powders, with the particle size of 50-500nm. The American Sulzer2MetCo atmospheric plasma spraying system and F42MB spray gun were used to prepare the coating. The thickness of both coatings was about 50.
1.2 The coating performance test uses Vickers microhardness juice to measure the Vickers hardness of the coating sample surface, and the sample is polished and polished. According to the provisions of ISO-4516-2002 Measurement Method for Vickers and Knoop Hardness of Metallic Coatings, the loading time is 5s, and the full load time is 10s. For which sample, five consecutive points are measured, and the arithmetic mean value is taken. The distance between two indentation centers or between any indentation center and the edge of the sample is not less than 3mm. The cross section morphology of the coating was observed by JSM-5900 scanning electron microscope (SEM) of Japanese JEOL company. The friction and wear test is carried out by MM Wl universal friction and wear tester. According to the provisions of ASTM-G99-2004 Pin on Disc Friction and Wear Test Standard, the upper sample is CY5SnBiM nickel base alloy (ASME standard material) pin (5mm 12.7mm), which is the valve seat material with high-speed nickel tungsten coating at the brush plating position, The lower sample is a 40Crl3 steel disk (60mm 15mm) sprayed with Al2O3-TiO2 and WC Co cermet coatings. Before the test, the samples are finely ground to make its surface roughness Ra be 0.2~0.3.

The main features of the pneumatic telescopic butterfly valve are as follows: novel and reasonable design, unique structure, light weight, convenient operation, quick opening and closing; The telescopic butterfly valve can not only adjust and intercept the flow, but also compensate for the expansion and contraction caused by the temperature difference of the pipeline, and also provide convenience for installation, replacement and maintenance of the valve. The sealing part can be adjusted and replaced, and the sealing performance is reliable.