There is tensile stress in the chromium plated coating, which has a very adverse effect on the fatigue resistance of the substrate. However, for spraying coatings, the deposited coating can be ensured to be in a compressive stress state by precisely controlling the deposition process. The test results show that the spraying coating has little effect on the fatigue resistance of the substrate. The room temperature high cycle (HCF) and low cycle (LCF) fatigue tests (Figure 6) on chromium plated samples and sprayed coatings show that the fatigue strength of the sprayed coating test is slightly reduced, while the chromium plated samples are significantly reduced, indicating that the impact of the application of sprayed coatings on the fatigue life will be smaller than that of chromium plated coatings.

2. Classification according to sealing surface material
(1) Soft seal butterfly valve 1) The sealing pair is composed of non-metallic soft materials and non-metallic soft materials. 2) The sealing pair is composed of metal hard materials and non-metallic soft materials.
(2) Metal hard seal butterfly valve. The sealing pair is composed of hard metal material to hard metal material.