Inch bolt surface treatment effect
Inch bolt is a kind of fastener widely used in machinery, construction, automotive and other fields, its surface treatment not only affects the appearance of the bolt, but also directly affects its corrosion resistance, wear resistance, friction coefficient, conductivity and other properties. The choice of surface treatment depends on the use of the bolt environment, material characteristics and performance requirements. The following is an analysis of several common inch bolt surface treatments and their effects.
1. Zinc Plating
Electrogalvanizing is one of the most common surface treatments for inch bolts. By plating a layer of zinc on the surface of the bolt, corrosion of the bolt in a humid environment can be effectively prevented. The zinc layer has good corrosion resistance, especially in neutral or weakly acidic environments. The surface of the bolt after electrogalvanizing is silver white and has a certain gloss.
Effect:
Corrosion resistance: The electrogalvanizing layer can form a dense oxide film, effectively isolating the contact between the bolt and the external environment, delaying the occurrence of corrosion.
Aesthetics: The surface of the bolt after galvanizing is smooth and uniform, and the appearance is beautiful.
Cost effectiveness: The electrogalvanizing process is mature, the cost is relatively low, and it is suitable for mass production.
Limitations: In strong acid or alkali environments, the corrosion resistance of the zinc layer decreases significantly. In addition, the thickness of the electrogalvanizing layer is limited, usually 5-25 microns, and corrosion may still occur after long-term exposure to harsh environments.
2. Hot-Dip Galvanizing
Hot dip galvanizing is to immerse the bolt into the molten zinc liquid, so that the zinc layer and the bolt surface metallurgical bonding, forming a layer of thicker zinc layer. Compared with electric galvanizing, hot-dip galvanizing has a thicker zinc layer, usually 50-150 microns, so it has better corrosion resistance.
Effect:
Corrosion resistance: The thickness and densification of the hot dip galvanizing layer gives it excellent corrosion resistance in harsh environments, especially for outdoor or Marine environments.
Wear resistance: Due to the thick zinc layer, the wear resistance of hot-dip galvanized bolts is good and can withstand certain mechanical wear.
Appearance: The surface of the bolt after hot dip galvanized is usually gray, the surface is rough, and it is not as smooth as electric galvanized.
Cost: The cost of hot dip galvanizing is high, and the process is complex, which is suitable for occasions with high corrosion resistance requirements.
3. Dacromet Coating
Dacromet treatment is an environmentally friendly surface treatment technology that forms an inorganic metal coating by dipping bolts into a solution containing metal particles such as zinc and aluminum. Dacromet coating has excellent corrosion resistance, high temperature resistance and chemical resistance.
Effect:
Corrosion resistance: The corrosion resistance of Dacromet coating is better than that of electric galvanizing and hot dip galvanizing, especially suitable for high salt spray and high humidity environment.
High temperature resistance: Dacromet coating can remain stable in high temperature environment, suitable for high temperature conditions.
Environmental protection: Dacromet treatment process does not produce harmful substances, in line with environmental requirements.
Appearance: Dacromet coating is usually silver gray, smooth surface, with good decorative.
Cost: Dacromet processing costs are higher, but because of its excellent performance, it is suitable for high-end applications.
4. Black Oxide Coating
Oxidation treatment is the formation of a black oxide film on the surface of the bolt by chemical or electrochemical methods. The oxide film is thin, usually 1-3 microns, which mainly plays a role in rust prevention and aesthetics.
Effect:
Rust resistance: the oxide film has a certain anti-rust ability, but it is not as good as electric galvanizing or hot dip galvanizing.
Aesthetics: The surface of the oxidized bolt is black and has good decoration, which is often used in occasions where a black appearance is required.
Coefficient of friction: Oxidation treatment can reduce the coefficient of friction on the bolt surface, making it easier to tighten when assembling.
Cost: The cost of oxidation treatment is low, suitable for occasions with low requirements for rust prevention.
5. Phosphating
Phosphating is to form a phosphate film on the surface of the bolt to improve the corrosion resistance and wear resistance of the bolt. The phosphating film is usually gray or black and has a thickness of 1-10 microns.
Effect:
Corrosion resistance: The phosphating film has a certain corrosion resistance, but it is not as good as electric galvanizing or hot dip galvanizing.
Wear resistance: phosphating film can improve the wear resistance of the bolt surface, suitable for occasions that need to withstand friction.
Lubricity: The phosphating film has good lubricity, which can reduce the friction resistance of the bolt during assembly.
Cost: The cost of phosphating is low, and it is suitable for occasions where corrosion resistance and wear resistance are not required.
6. Stainless Steel Passivation
Stainless steel bolts usually do not require additional surface treatment because stainless steel itself has good corrosion resistance. However, in order to further improve its corrosion resistance, stainless steel bolts can be passivated, that is, a dense oxide film is formed on the surface.
Effect:
Corrosion resistance: Passivated stainless steel bolts have a longer service life in corrosive environments.
Aesthetics: The surface of the bolts after passivation is smooth and bright, and has good decoration.
Cost: The cost of passivation treatment is low, suitable for stainless steel bolts with high corrosion resistance requirements.
7. Organic Coating
Organic coating is the coating of a layer of organic material, such as paint, powder coating, etc., on the surface of the bolt. Organic coatings can provide good corrosion resistance and decorative, suitable for occasions where a specific color or appearance is required.
Effect:
Corrosion resistance: The organic coating can effectively isolate the contact between the bolt and the external environment, providing good corrosion resistance.
Aesthetics: Organic coatings are available in a variety of colors and looks to meet different decorative needs.
Wear resistance: Organic coatings have poor wear resistance and are susceptible to mechanical wear.
Cost: The cost of coating organic coating is higher, suitable for occasions with high decorative requirements.
conclusion
There are a variety of surface treatments for inch bolts, each with its own unique advantages and limitations. The choice of suitable surface treatment requires comprehensive consideration of the use of the bolt environment, performance requirements and cost factors. Electrogalvanizing and hot-dip galvanizing are the most common treatment methods, suitable for most conventional applications; Dacromet treatment is suitable for high corrosion resistance and high temperature occasions; Oxidation treatment and phosphating treatment are suitable for occasions where rust prevention and wear resistance are not required; The passivation treatment of stainless steel bolts can further improve its corrosion resistance; Organic coatings are suitable for applications that require a specific appearance. Reasonable selection of surface treatment can effectively prolong the service life of bolts and improve their performance and reliability.