The common anticorrosive technology of titanium nut and other fasteners is introduced and summarized

The simple understanding of fasteners is that we often say titanium nuts, bolts and other mechanical equipment used for fastening connection parts. For fasteners, corrosion and rust is one of the main forms of failure. Once the fastener is corroded and rusted, it will affect the detachable and repeated installation of the thread, and then damage the connection between the parts, leading to serious consequences. Therefore, the corrosion protection of fasteners has always been a topic of great concern to us. We briefly introduce the anti-corrosion technology of fasteners from the following three aspects.

First, one of the commonly used anti-corrosion technologies of fasteners: film treatment technology
Membrane treatment technology mainly refers to the use of chemical or electrochemical methods to generate a layer of stable chemical (electrochemical) conversion film on the surface of the metal processing technology. For example, in urban rail vehicles, the fasteners are treated with black/blue film and phosphating.

The advantages of black/blue treatment are: low hydrogen embrittlement sensitivity, can be used as degree bolt; The color is brighter, the decorative effect is better; The cost is low.

The advantages of phosphating are: as a fastener, its torque-preload consistency is very good; Hydrogen embrittlement sensitivity is low, can be used as degree bolt; The cost is lower.

Two, fasteners commonly used anti-corrosion technology two: metal coating technology
Metal coating technology is mainly used on the surface of metal materials to form a thin layer of metal, in order to give metal materials decorative or protective surface treatment technology. Commonly used metal coatings are zinc plating, chromium plating, nickel plating, silver plating, cadmium plating and so on.

Among them, galvanizing is widely used in fasteners. Galvanizing is divided into hot dip galvanizing, electric galvanizing and mechanical galvanizing. The advantage of hot dip galvanizing is that the coating thickness is very thick, and its corrosion resistance is very good. It is widely used in outdoor steel parts for a long time (such as TV tower, highway guardrail, etc.). For fasteners, hot-dip galvanizing is generally suitable for M6 and above bolts, but it cannot be used for degree fasteners. This is mainly because the operating temperature of hot-dip galvanizing process is very high, which is easy to temper and soften degree fasteners.

The thickness of the zinc layer of electric galvanizing is thin, and the corrosion resistance is poor in the galvanizing anticorrosion treatment, but its process is simple, the cost is low, and the influence on the threading problem is also small. It is widely used in fasteners, but the electric galvanizing can not be used in degree fasteners. The surface of mechanical galvanizing layer is compact and uniform, the decorative effect is good, the corrosion resistance, and the coating has no high temperature tempering, no hydrogen embrittleness and other shortcomings of hot dip galvanizing and electric galvanizing, which is a surface treatment process especially suitable for fasteners anticorrosion.

Chromium plating process is complex, expensive, before chromium plating nickel or copper plating, but chromium as a metal coating has strong adhesion, good wear resistance, decorative effect, and has high heat resistance characteristics.

Nickel plating is also an ideal plating treatment for fasteners. Nickel plating has excellent electrical conductivity, high hardness, good decorative effect and good heat resistance, but its disadvantages are complex technology and expensive price.

Cadmium plating is especially suitable for fasteners used in Marine environment (such as those used in Hainan Sea aircraft and oil drilling platforms); Silver plating is suitable for electronic, electrical, high frequency components and other fields (such as generator conductive bolt, vehicle battery lead terminal). Both are also complicated and expensive.

Three, fastener commonly used anticorrosion technology three: coating technology
Coating technology refers to a surface treatment technology in which a specific coating is coated on the surface of titanium nuts with certain equipment and methods to generate a compact, continuous and uniform film on the surface, and then dried and cured by natural or artificial methods to form a protective or decorative coating. In fasteners, the coating technology is mostly used in zinc chromium coating technology, which is coated with zinc chromium coating on iron and steel parts, after full closed cycle coating baking and forming a coating on the surface of iron and steel parts, also called Dacro treatment. Dacrol processing price is moderate, as a fastener, its torque-preload consistency is very good, and there is no hydrogen embrittleness sensitivity, but at the same time, poor wear resistance, poor decoration, poor conductivity.