Metals play important roles in supporting structures and helping the systems yield the desired products. Given that they are likely to be used in highly sensitive processes with extreme conditions, they have to be coated with special alloys or materials to avoid contamination of the yield as well as working on the structures as a result of erosion, corrosion, and oxidation. The diffusion coatings involve coating the metal surface with a material that is resistant to corrosion.
While alloys are known to help reduce the rate of corrosion, they are likely to leach metal ions into the process stream. This renders them unsuitable in systems where high purity environment is necessary to avoid process contamination. Coating a stainless steel give them high corrosion resistance properties while protecting the process from contamination from leached metal ions.
This makes the metals reliable and long lasting thereby allowing for the manufacture of critical machine components and components for other applications. The process is used to manufacture and process gas turbine components such as cases, blades, vanes, and gate valves, pump impellers as well as power generation components.
The level of resistance offered to the base metals enables them to work effectively in conditions of temperatures as high as 2100 degrees Fahrenheit with no risk of spallation. As such, all metallic components of the machine or system that is exposed to extreme temperature, pressure, pH level and other physical conditions have to be diffusion coated.
This is not to say that you can just walk into the store and order any coated metal plate, the price is less of a factor than the operational conditions. Not all the coating materials offer the same level of resistance under a similar set of conditions. As such, you have to consider the conditions under which the metal is to be used and make a wise choice.
Compatibility is perhaps the most important factor to consider. No single coating or alloy is able to withstand corrosive attack from all types of acids and bases. Your choice of the coating material should be guided with all potential chemical exposures, including air and water.
Different levels of chemical or gas concentration have varying effects on the rate of corrosion. In most cases, the highly concentrated acids and bases tend to increase the rate of erosion. In addition to the concentration level, the fluid velocity and type must also be considered to find the most compatible coat.
The other factor is the period of exposure. A metal corrodes faster when exposed to the corrosive element for longer time period. The situation where the metal is exposed to the high temperature or acidic environment periodically, it is wetted and dried without rinsing in the process, the rate of corrosion is significantly accelerated.
The pH also matters a lot. While silicon performs very well in low pH (acidic) conditions, the same is not the case in high pH (basic) condition. In fact, silicon is likely to dissolve in a high pH environment. Lastly, high temperature increases the rate of reaction and diffusion. This significantly impacts the materials like stainless steel and aluminum that depends on passive film to prevent corrosion. Silicon is able to stand high temperatures of up to 1000c, acting as a barrier to diffusion and oxidation.
While alloys are known to help reduce the rate of corrosion, they are likely to leach metal ions into the process stream. This renders them unsuitable in systems where high purity environment is necessary to avoid process contamination. Coating a stainless steel give them high corrosion resistance properties while protecting the process from contamination from leached metal ions.
This makes the metals reliable and long lasting thereby allowing for the manufacture of critical machine components and components for other applications. The process is used to manufacture and process gas turbine components such as cases, blades, vanes, and gate valves, pump impellers as well as power generation components.
The level of resistance offered to the base metals enables them to work effectively in conditions of temperatures as high as 2100 degrees Fahrenheit with no risk of spallation. As such, all metallic components of the machine or system that is exposed to extreme temperature, pressure, pH level and other physical conditions have to be diffusion coated.
This is not to say that you can just walk into the store and order any coated metal plate, the price is less of a factor than the operational conditions. Not all the coating materials offer the same level of resistance under a similar set of conditions. As such, you have to consider the conditions under which the metal is to be used and make a wise choice.
Compatibility is perhaps the most important factor to consider. No single coating or alloy is able to withstand corrosive attack from all types of acids and bases. Your choice of the coating material should be guided with all potential chemical exposures, including air and water.
Different levels of chemical or gas concentration have varying effects on the rate of corrosion. In most cases, the highly concentrated acids and bases tend to increase the rate of erosion. In addition to the concentration level, the fluid velocity and type must also be considered to find the most compatible coat.
The other factor is the period of exposure. A metal corrodes faster when exposed to the corrosive element for longer time period. The situation where the metal is exposed to the high temperature or acidic environment periodically, it is wetted and dried without rinsing in the process, the rate of corrosion is significantly accelerated.
The pH also matters a lot. While silicon performs very well in low pH (acidic) conditions, the same is not the case in high pH (basic) condition. In fact, silicon is likely to dissolve in a high pH environment. Lastly, high temperature increases the rate of reaction and diffusion. This significantly impacts the materials like stainless steel and aluminum that depends on passive film to prevent corrosion. Silicon is able to stand high temperatures of up to 1000c, acting as a barrier to diffusion and oxidation.
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