Which Surface Treatment is good for heat sinks?

You may have heard of terms like "passivation," "natural anodizing," and "black anodizing," which represent various surface treatments for aluminum alloy components. Surface treatment is not only about the aesthetic appearance of the product but also a crucial technical parameter. Surface treatment mainly affects the following three characteristics:

 

1) Wear Resistance - The surface of ordinary aluminum alloy (whether it's the casing or the heat sink) has the typical "aluminum" color (natural aluminum). For example, after wiping with bare hands, you may often find black marks on your hands, which are actually a thin layer of aluminum and its oxide. Aluminum is a relatively soft metal with low wear resistance when untreated. After electrolytic oxidation (anodizing) surface treatment, the oxide layer formed on aluminum is much thicker than that generated under normal conditions. The deposited A5O is a very hard material, making the surface highly wear-resistant.

 

 

2) Chemical Resistance - In a clean and dry environment, aluminum alloy is classified as a "corrosion-resistant" material. However, aluminum itself easily reacts with various acids and bases. Even fingerprints, if not promptly removed, can lead to oxidation over time. However, a surface treated with anodizing enhances corrosion resistance, effectively protecting the aluminum surface even under harsh conditions. This is why aluminum components used outdoors are often anodized.

 

4)Cooling Efficiency - Lastly, and most importantly, the parameter of cooling efficiency. The untreated natural aluminum surface has a very low emissivity (emissivity is a parameter of the surface's thermal radiation ability). The emissivity of most materials is around 0.95, while natural aluminum has an emissivity of only about 0.05. This means that if an aluminum heat sink relies solely on radiative heat dissipation, its efficiency will be very low. However, a heat sink surface that has undergone natural anodization has a higher emissivity than a natural aluminum surface, approximately around 0.80. Of course, convection also contributes to heat transfer, depending on the size of the heat sink surface and the way air heats the heat sink.

 

 

ZP Group has been engaed in aluminum deep-processed products and heat sinks customization for 19 years, and we have thousands of successful cooperation cases all over the world. Contact us for the first step of your successful project.