The surface treatment of screws, as a key link to improve their corrosion resistance, wear resistance and aesthetics, cannot be ignored. Today, let's take a deep look at several common methods of screw surface treatment: galvanizing, nickel plating, blackening.
Author: Marisa
The surface treatment of screws, as a key link to improve their corrosion resistance, wear resistance and aesthetics, cannot be ignored. Today, let's take a deep look at several common methods of screw surface treatment: galvanizing, nickel plating, blackening.
Galvanizing: A classic choice for anti-corrosion
Galvanizing, that is, plating a zinc layer on the surface of the screw, is a common anti-corrosion treatment method. Zinc has good corrosion resistance and sacrificial anode protection. When the zinc coating is damaged, zinc can be corroded preferentially as the anode of the galvanic cell, thereby protecting the base metal from corrosion. In addition, the zinc coating also has good decorative properties and certain wear resistance.
There are many kinds of galvanizing processes, including hot-dip galvanizing, electro-galvanizing, and mechanical galvanizing. Among them, hot-dip galvanizing is to immerse the screw in molten zinc liquid to form a thicker zinc coating, which is suitable for anti-corrosion needs in harsh environments; electro-galvanizing is to deposit a thinner zinc layer on the surface of the screw through electrolysis, which is suitable for decoration and mild anti-corrosion in general environments.
Nickel plating: the perfect combination of beauty and durability
Nickel plating is to plate a layer of nickel on the surface of the screw to improve its corrosion resistance, wear resistance and aesthetics. The nickel layer has good chemical stability and is not easily oxidized and corroded, so nickel-plated screws can maintain a long service life even in harsh environments. At the same time, the nickel layer also presents a silvery-white metallic luster, which makes the nickel-plated screws have a better decorative effect.
The nickel plating process mainly includes electroplating and chemical plating. Electroplating nickel is to deposit a layer of nickel on the surface of the screw through electrolysis. The process is mature and widely used; chemical nickel plating uses a chemical reduction reaction to form a uniform nickel-phosphorus alloy layer on the surface of the screw, which has better wear resistance and corrosion resistance.
Blackening: Modern Application of Traditional Technology
Blackening is a surface treatment method that oxidizes the surface of the screw to form a black or blue-black oxide film. This oxide film has certain corrosion resistance and lubricity, which can reduce the wear and corrosion of the screw during use. At the same time, the blackening treatment can also make the surface of the screw present a uniform black or blue-black color, which has a certain decorative effect.
The blackening process mainly includes alkaline blackening and acid blackening. Alkaline blackening is to immerse the screw in an alkaline solution containing sodium hydroxide, sodium nitrite and other ingredients to form an oxide film through an oxidation reaction; acid blackening is to immerse the screw in an acidic solution containing nitric acid, sulfuric acid and other ingredients to form an oxide film through an oxidation reaction. The two processes have their own characteristics and are suitable for different 9 screw materials and processing requirements.