What is Metal Corrosion? The Definition?
Corrosion is a degradation of materials' properties caused by chemical reaction with their environments. For example, the corrosion of iron is due to interact by oxygen and water to produce rust.
Different Type of Corrosion
The impacts of Corrosion
The direct cost of corrosion to U.S economy in 1998 is close to 3.1 % of Gross National Product (GNP) and the data equals to $275.7 billion.
Methods of corrosion prevention
Marine and electronic equipments are suffering from corrosion because of contamination by salt and water into the concrete.
The proven methods of dealing with corrosion prevention are
- Select anti-corrosion material
- Enclosure Design to prevent corrosion
- Painting treatments on the surface
- Chemical Conversion Coating treatment on the surface
- Electroplate treatment on the surface
- Operating environment control
- Anodizing (Anodic Oxidation)
Two ways of corrosion protection:
- Positive Passivity:Anodic Protection
- Negative Immunity:Cathodic Protection
Pourbaix Diagram of Iron/Steel
Pourbaix Diagram of Aluminum and its alloy
How does Winmate test/ verify its anti-corrosion products?
Salt spray test is a standardized test which widely used in the Marine/ industrial products to evaluate different corrosion prevention methods.
Test Equipment: Winamte’s Salt-mist test Machine – Weiss/ SC450 in National Taiwan University
Test period depends of the corrosion resistance of the coating; the more prevention of corrosion the longer the period in testing without showing appearances of corrosion.
Refer to IEC60945:2002, Section 8.12
Test sequence-1: Salt spray test, exposing for 2 Hours
At temperature 35C
Saline solution: 5% NaCl, PH 6.5 to 7.2
Quantity of fog: 1.0~ 2.0ml/80 cm2 / hour
Test sequence-2: Humidity storage test, exposing for 168 Hours
Storage Temperature: 40C
Humidity in chamber during storage: 93%
Above test sequences shall perform for 4 cycles
*1. Data source: Dr. Rolly Luo, Dept. of Advanced Electrochemistry & Corrosion Prevention, Material and Chemical Research Laboratories, Industrial Technology Research Institute, Taiwan.