A Study Of Alumina Foam Ceramic And The Formation Of Sol Coating On Its Surface

With the rapid development of science and technology, the electrical motor is upgrading very fast, in this situation we need a new electrical-motor-brush with high-performance, especially on the wear resistance and electrical conductivity,so how to prepare a high-performance electrical-motor-brush is the focus of our work.And the high volume fraction Al2O3/Cu based composite material prepared by pressureless infiltration method can satisfy the high-performance demond about the electrical-motor-brush. However, the bad wettability between Cu and Al2O3 limits the application of pressureless infiltration method. This paper mainly has two purposes:Frist,preparing foam ceramics with good mechanical properties; second, use Sol-Gel method to form Titanium Oxide coat on the skeleton of foam ceramics, this coat can develop the wettability between Cu and Al2O3.In this paper we mainly researched on the whole process of manufacturing foam ceramics by replicating organic foams method.Took Al2O3 and SiO2 as the basic materials,used the following two options to sinter corundum/mullite multiphase foam ceramic:Al2O3/other materials(SiO2, Kaolin, Bentonite and Talc)series;Al2O3/SiO2/Silica solution serials.Then analysed the various factors during the preparation process of foam ceramics to get the best preparation parameters.Compared the the performance of foam ceramics obtained by the two options:to the first option,when the final sintering temperature was 1550℃, the foam ceramics can obtain a good sintering effect, also had a certain strength, thermal shock resistance, the main crystalline phase was corundum, and the connecting phase was Mullite; to the second option, with the Al2O3 as the basic material, added the SiO2 powder and Silica solution, sintered in1550℃, we obtained another kind of foam ceramics,but the mechanical properties of it was bad, can not be used in actual production, the main crystalline phase was Mullite, with little corundum. Also this paper focused on the technology that how to coat the foam ceramics with Titanium Oxide. Because foam ceramics has three-dimensional network structure, the Titanium Oxide sol is difficult to deposite on the skeleton of foam ceramics, this paper use vacuum infiltration method to coat the foam ceramics.After the experiment, this paper analysed the impact of dipping time and number of dipping process to the Titanium Oxide sol surface.The experiment confirmed that dipping two times,20 minutes every-time, can obtain the uniform coat of Titanium Oxide.At last from the scanning electron microscopy,we can see the uniform Titanium Oxide coat in the skeleton of the foam ceramics, and had good interfacial bonding between them.In summary, this paper has received the best process parameters to manufacture foam ceramics, while also accessed to a suitable dipping process parameters.