What are the surface modification methods for alumina powder?

Aluminum oxide, a common material, is commonly used in the production of ceramics, coatings, catalysts, etc. However, in some applications, such as filling composite materials or preparing high-performance catalysts, surface modification of alumina is required to improve its performance and stability. This article will discuss the surface modification methods of alumina.

Surface modification is the process of introducing a certain substance (modifier) into the surface of another substance (material to be modified) to improve the properties and functions of the material. The commonly used processes for surface modification of alumina include chemical treatment, deposition, and other methods, among which the most common is the modification of alumina by silane coupling agent (KH-560).

Silane coupling agent (KH-560) is a versatile organic silicon compound with good surface affinity and reactive properties. It can react with the surface of alumina to form chemical bonds, thereby achieving stable surface modification. When using KH-560 for modification, attention should be paid to factors such as the amount added, pre hydrolysis pH value, pre hydrolysis time, reaction temperature, reaction time, and stirring rate to ensure the desired modification effect.

The specific modification method is to first prepare a solution with an alcohol water ratio of 1:8, add an appropriate amount of KH-560, stir evenly, and the amount of KH-560 should be KH-560: alcohol: water=20:9:72. Then use 40% acetic acid to adjust the pH value, pre hydrolyze it for 1 hour, reaction temperature is 60 ℃, and stirring rate is 1500r/min. After pre hydrolysis of KH-560, fully disperse micrometer sized Al2O3 in an appropriate amount of ethanol for about 1 hour. Slowly add a certain amount of KH-560 to the uniformly dispersed micrometer sized alumina for a mixing reaction. After the reaction is completed, filter and wash three times with ethanol. Dry at 60 ℃ for 3 hours to obtain the modified alumina material.

To verify the modification effect, various tests and characterizations such as oil absorption value, viscosity, SEM, and FTIR can be carried out. The experimental results showed that KH-560 was successfully grafted onto the surface of alumina powder, and the modified powder had smooth particle edges and no obvious agglomeration phenomenon. Meanwhile, the oil absorption value of the modified alumina powder decreased by 43.4%, and the viscosity decreased by about 16.1%. This indicates that the surface modification method of alumina can effectively improve its physical and chemical properties, thereby adapting to a wider range of application fields.

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