Everyone knows that if drywall screws are exposed to hu […]
Everyone knows that if drywall screws are exposed to humid air for a long time, they will rust, so what measures should we take to avoid this problem? Will the surface avoid rust if treated a little bit?
The surface treatment of high-strength wallboard screws is the process of forming a covering layer on the surface of the workpiece by a certain method. Its purpose is to give the product a beautiful surface and anti-corrosion effect. The surface treatment methods are all attributed to the following two methods:
1. Electroplating: Immerse the parts to be electroplated (drywall screws) in an aqueous solution containing the metal compound to be deposited, and pass the plating solution with current to precipitate the electroplated metal and deposit it on the parts. Generally electroplating has galvanized, copper, nickel, chromium, copper-nickel alloy, etc. Sometimes boiled black, phosphating, etc. are also included. That is the galvanized drywall screws and the market;
2. Hot-dip galvanizing: This is done by immersing the carbon steel parts in a molten zinc plating tank with a temperature of about 510 ° C. As a result, the iron-zinc alloy on the surface of the steel part gradually becomes passive zinc on the outer surface of the product. Hot dip aluminum plating is a similar process.
The surface of the strength wallboard nails () is not allowed to be partially uncoated, scorched, rough, dark, peeling, skinning and obvious streaks, pinholes, black slag, loose passivation film, turtle Cracks, shedding and severe passivation marks. In other words, the surface treatment is not so easy. Below we introduce the coating thickness and distribution of the strength wallboard screws:
1. Coating thickness:
The operating life of a fastener in a corrosive atmosphere is proportional to its coating thickness. The generally recommended thickness of economical plating is 0.00015in ~ 0.0005in (4 ~ 12um).
Hot-dip galvanized: The standard average thickness is 54um (called diameter ≤3 / 8 is 43um), and the minimum thickness is 43um (called diameter ≤3 / 8 is 37um).
2. Distribution of coating:
Using different deposition methods, the way the plating layer accumulates on the surface of the fastener is also different. During electroplating, the coating metal is not deposited uniformly on the outer peripheral edge, and a thick coating is obtained at the corner. In the threaded part of the fastener, the thickest coating is located on the crest of the thread, gradually thinning along the side of the thread, and the thinnest is deposited at the bottom of the tooth, while hot dip galvanized is just the opposite. The thicker coating is deposited on the inner corner and At the bottom of the thread, the metal plating tendency of the mechanical plating is the same as that of hot dip plating, but it is smoother and the thickness is much more uniform on the entire surface.