Anleolife Garden View: Get Rid of The Bolt-rust Trouble from Your Raised Garden Bed

Accompanied by the last blog post which analyses Why Galvanized Metal Raised Garden Bed Succeeds in Keeping Rust-resistant, this post is about to continue with that subject but focus on the part easily ignored by gardeners: bolts and nuts from your raised garden bed that tend to rust as well. Besides galvanization there is another anti-rust technic applied to protect bolts and nuts—Dacromet. Let’s look into it.

Dacromet Coating on Fasteners

Dacromet is a water based inorganic coating mainly comprising of overlapping zinc and aluminum flakes with an inorganic binder. This Zinc Aluminum flake combination offers 4 way protection as:

1.Barrier Protection : Overlapping zinc and aluminum flakes provide an excellent barrier between the steel substrate and the corrosive media

2.Galvanic Action : Zinc corrodes to protect steel

3.Passivation : Metal oxides slow down the corrosion reaction of zinc and steel to provide 3 times greater corrosion protection than pure zinc

4.Self-Repairing : Zinc oxides and carbonates migrate to the damaged area of the coating to actively repair the coating and restore barrier protection

Dacromet can be applied by Dip-Spin, Spray or Dip-Drain (Spin) using bulk or rack. This type of coating is primarily used in marine, agriculture, construction equipment, wind turbine installation, aerospace and heavy automotives.

Dacromet is a new kind of surface treatment technology. Compared with the painful electroplating technology, Dacromet can be said to be a kind of “green plating”. So, what are the advantages of Dacromet bolts compared with other bolts?

The advantages of Dacromet are as follows:

1. Although the thickness of the Dacromet film is only 4-8μm, its anti-rust effect far exceeds the traditional electro-galvanizing, hot-dip galvanizing or paint coating method, so Dacromet bolts also have excellent anti-corrosion properties. Rust effect.
2. Dacromet’s processing technology determines that Dacromet bolts will not appear hydrogen embrittlement, so Dacromet bolts are very durable.
3. Dacromet bolts are very resistant to high-temperature corrosion, and the heat-resistant temperature can be as high as 300℃. The traditional galvanizing process is far inferior to it.
4. Good adhesion and recoating performance: The coating on Dacromet bolts can produce good adhesion with the metal substrate in contact, and it has strong adhesion with other coatings. The processed parts are easy to color. The bonding force with the organic coating even exceeds that of the phosphating film.
5. Dacromet bolts will not produce gas and sewage that are good for the natural environment during the entire process of production, processing and coating coverage, and no subsequent treatment is required, which greatly reduces the treatment cost.

 Dacromet Plated Bolts and Nuts

Dacromet Plating is in fact a water based, environment friendly process of zinc and aluminum coating in chromate solution with low friction coefficient that facilitates bolts and nuts with the means to resist corrosion against high humidity and high temperature.

Dacromet Plated bolts and nuts don’t face hydrogen embrittlement as opposed to hot-deep-galvanized bolts and nuts, since the coating temperature for Dacromet process is substantially lower than hot deep galvanization and is considered the best possible coating method for bolts and nuts. Further more, some standards of bolts such as ASTM A490 and ASTM A354 DB are prohibited to be hot deep galvanized due to the connection failure caused by hydrogen embrittlement.

Dacromat Plating involves submerging bolts and nuts in a water solution of zinc and aluminum - aluminum with substantially lower percentage - along with Chromate as solvent in 100 degrees Celsius, for zinc and aluminum particles to take position in layers on the surface of the fasteners. After extracting the bolts and nuts from zinc tub, they are usually centrifuged to lose the redundant particles and then are heated by 300 degrees Celsius so that the layers of zinc and aluminum are very well baked on the surface. In order to have a highly resistant layer the entire process is repeated once more to form a firmly thick, low friction coefficient, blurry silver layer on top of the bolts and nuts.

Dacromet Plating Thickness

Dacromet Plating provides a much thinner layer compared to hot deep galvanized plating. Each micrometer of Dacromet layer resists 100 hours of salt spray - with high corrosion properties - which is almost 4-5 times higher than each micrometer hot deep galvanized plating. Dacromet plating is usually done in three different grades as follow

Grade A 5-7 Micrometer 24 grams coating per square meter

Grade B 8-10 Micrometer 36 grams coating per square meter

Grade C 10-12 Micrometer 42 grams coating per square meter

Bolts and nuts and fasteners in general are usually manufactured having Grabe B of Dacromet coating resistant to 800-1000 hours salt spray. Experiment relieved that hot deep galvanized bolts would suffer equal corrosion after 75 hours as Dacromet bolts would after 360 hours.

(Anleolife raised garden bed with Dacromet screws and wingnuts)