Application skills of common rust and corrosion inhibitors in metal working fluids

May 29, 2024

Application skills of common rust and corrosion inhibitors in metal working fluids

There are many kinds of corrosion inhibitors, and the corrosion inhibition mechanism is complex. The correct use of corrosion inhibitors can adsorb them on the surface of parts and prevent the corrosion of water and oxygen in the air on the metal surface. The purpose is to passivate the corrosion rate within a controllable range. Improve the corrosion resistance of parts in use.

The advantages and disadvantages of common anti-rust and corrosion agents and their application in metal working fluids are introduced

1. Borate/ester

Borate/ester is a widely used water-soluble anti-rust agent at present, which is especially effective for rust prevention of cast iron, and can be used in synthetic cutting fluid, semi-synthetic cutting fluid and water-based grinding fluid.

01 Borate:

Good rust prevention, low cost; In solution, it is easy to hydrolysis reversible reaction, with the consumption of alkali, boric acid will precipitate and corrode the metal.

02 Borate:

High alkali reserve, stable pH value of the system; It has good wear reduction and antiwear performance. It has certain bacteriostatic and bactericidal functions.

Borate/ester used alone, the effect is not ideal, need to be combined with other rust prevention agents; Borate combined with different carboxylate salts has good anti-rust properties for ferrous metals.

Disadvantages: long-term use is easy to sticky, affecting cleaning.

2. Molybdate

Molybdate: nitrite = 2:3, the total concentration of 5mg/L, has a good corrosion inhibition on carbon steel;

Sodium molybdate: monoethanolamine = 1:5, has a good corrosion inhibition effect on steel;

Molybdate +BTA+ sodium benzoate + amine has a good anti-corrosion effect on steel and cast iron.

Molybdate is a low-toxicity, pollution-free Corrosion Inhibitor, as a corrosion inhibitor, the advantages are as follows:

① The corrosion inhibition effect is good, and the combination of other corrosion inhibitors can inhibit the occurrence of pitting corrosion;

② It has a good corrosion inhibition effect on common metal materials such as carbon steel, copper, brass and aluminum;

③ Low toxicity;

④ It is widely used and effective in both soft and hard water.

Disadvantages: The dosage is relatively large, the cost is relatively high.

3. Sulfonate and other oil-based rust prevention agents

01 Petroleum barium sulfonate T701

Solids: 50%, liquids: 50%. Solid T701 has good oil solubility after heating, and has good anti-rust properties for black and non-ferrous metals. It is used for Anti-rust Oil, oil-based products, emulsified oil and micro-emulsified oil

02 Sodium sulfonate T702

Petroleum sodium sulfonate: has strong hydrophilicity, corrosion inhibition on metals, good rust resistance and emulsification properties, used in oil-based products, emulsified oil and micro-emulsified oil.

Synthetic sodium sulfonate: by heavy alkyl benzene sulfonation, neutralization, decolorization and preparation, HLB value of about 12, has a strong hydrophilic, corrosion inhibition on metals, is a good anti-rust agent and emulsifier. The hydrophilicity is obviously stronger than sodium petroleum sulfonate, the color is lighter, the emulsification range is wide, and the deployment is convenient, and it is an ideal additive for the preparation of micro-emulsified oil.

03 Zinc naphthenate T704

Good oil solubility, good rust resistance to steel, copper and aluminum, poor rust resistance to cast iron used alone, need to be combined with T701 to achieve good results, for oil-based products, emulsified oil and micro-emulsified oil. (Add amount: 3-10%)

04 Barium dinonylnaphthalene sulfonate T705

It has excellent anti-rust properties for all kinds of metals, good oil solubility stability, good lubrication and anti-wear properties, and good stability in wet conditions. Used as an Anti-Rust Additive in various petroleum and synthetic lubricants and greases; Used as an anti-rust agent in petroleum ether cleaning agent and water displacement anti-rust liquid.

4. Fatty acid salts, esters/amides

(1) Fatty acid salts: oleic acid/alkamine salt, tall oil/alkamine salt, C21 carbon dibasic acid/alkamine salt, dimeric acid/alkamine salt, etc.;

(2) Fatty acid esters: sorbitan monooleate (Span-80), etc.

(3) Alkyl amide: alkolamide, castor oil maleamide, nitrogen containing heterocyclic boramide, tall oil amide, etc.

Advantages: Both emulsification, cleaning, lubrication and rust prevention functions, in the system with high oil content, rust prevention is good in the low oil system.

Disadvantages: large foam, easy to corrupt.

5. Caprylic acid, neocapric acid/isononaic acid

Caprylic acid, neocapric acid/isononaic acid is mainly used in synthetic cutting fluid, especially in the total synthetic system containing polyether, in the alkaline system can couple polyether, improve the solubility of polyether in the alkaline system, assist the lubrication of polyether, itself has a certain anti-rust performance, and can improve the film formation of other anti-rust agents on the metal surface; It can also be used as a balancing agent in microemulsification and emulsification systems to adjust the balance of the system.

Disadvantages: The smell is relatively large, and the rust prevention is general.

6. Dibasic acid

01 Sebacic acid

It is generally prepared by separating castor oil after heat saponification and hot cracking. Castor oil is one of the most deeply processed vegetable oils in the world, and sebacic acid is its important downstream product, which is widely used as an anti-rust agent for water-based products.

Advantages: As a water-based rust inhibitor, hard water resistance is good, and the foam is relatively small.

Disadvantages: rust resistance is general, and the price has soared repeatedly in recent years, and the cost performance has become lower and lower.

02 undecane/dodecane dibasic acid

Long chain dibasic acid does not exist in nature, it can be combined with long chain dibasic acid by chemical method, but the chemical production of long chain dibasic acid has shortcomings such as technology, equipment requirements, high energy consumption, etc. At present, the production of long chain dibasic acid is gradually adopted by microbial fermentation.

Advantages: As water-based rust prevention agent, good rust prevention.

Disadvantages: poor resistance to hard water, large bubbles, easy corruption, in recent years, the price has soared again and again, cost-effective has become lower and lower.

The above is the Application skills of common rust and corrosion inhibitors in metal working fluids we have listed for you. You can submit the following form to obtain more industry information we provide for you.

You can visit our website or contact us, and we will provide the latest consultation and solutions

Share to:

Send Inquiry

Previou:Power tool grease selection, twice the result with half the effort!

Next:Why will the machine rust with anti-rust oil?