HOT LINE: +86-510-80628100Most corrosion is caused by improper material selection, and choosing new corrosion-resistant materials is the fundamental way to solve the problem of metal corrosion. Secondly, some corrosion is caused by the improper selection of protective layers (coating or plating, etc.), which cannot provide normal protection. The research on protective layer materials and processes plays a crucial role in promoting anti-corrosion technology. Even if the materials and protective layers are selected reasonably, defects in structural design can still cause corrosion, such as the accumulation of more corrosive deposits on rough parts surfaces and prolonged exposure to humid air, which can lead to corrosion over time. According to the test results, the anti salt spray measures for various types of specimens can be determined as follows:
(1) Joint type: 1Cr18Ni9Ti and 1Cr17Ni2 have excellent salt spray resistance. The outer nut and ball head made of stainless steel 1Cr18Ni9Ti have little corrosion and the best performance; The joint with substrate 1Cr17Ni2 showed no corrosion phenomenon after improving the surface smoothness; The anti salt spray effect of steel 45 joints and screw plugs with surface chemical nickel plating is average; The salt spray resistance of 2Cr13 joints is poor. Taking into account factors such as strength and assembly, 1Cr17Ni2 is preferred for the material of the screw in straight joint and plug, while 1Cr18Ni9Ti is selected for the outer nut and ball joint.
(2) Valve components: The purchased electromagnetic valve body has good anti salt spray performance after painting treatment. After painting the valve body of the purchased solenoid valve, the anti salt spray performance is good. The exposed electromagnetic parts are not coated and are more severely corroded. Due to the short working time and low heat dissipation of the solenoid valve, the actual product's electromagnet will also undergo painting treatment in the future. The coating thickness of the valve block sample is 8<12 μ m, with a phosphorus content of 5%~9%. After experimental verification, this process does not require reserved coating thickness during machining due to the relatively thin coating, which ensures both process processing and anti-corrosion effect.
(3) Piston rod: The sample rod plated with nickel and then hard chromium has excellent salt spray resistance. The piston rod is an executive component in hydraulic systems and is often directly exposed to salt spray environments, requiring higher corrosion resistance. The anti-corrosion performance of single-layer chrome plating is relatively poor, with mild corrosion observed in double-layer chrome plating. The corrosion area of electroplated nickel followed by hard chromium plating and nano nickel plating is 0, but the surface roughness of the latter is significantly reduced after salt spray testing. After comprehensive comparison, the surface coating of the piston rod adopts the process of "electroplated nickel+hard chromium plating".
(4) Plate and tube type: Fasteners are coated with marine 10036 coating; The material for stainless steel pipes is 1Cr18Ni9Ti; Copper gaskets have slightly poor salt spray resistance and can be used in specific situations such as high temperature environments. Combination gaskets can be used in other situations.
The above measures are applied to actual hydraulic system products, and in the structural design, grooves are avoided as much as possible to reduce the accumulation of salt spray. After a one-year assessment of the natural salt spray environment along the coast of Hainan, various products have shown good anti salt spray effects.
