Ceramic-based High-temperature Phase Change Thermal Storage Materials To Suppress - The Study Of The Sintering Process

In recent years, energy saving and environmental protection are the broad hot problem that gets solicitude always. As a kind of new saving-energy material has wide application prospect in industry. How will compose the ceramics and the phase change materials has also become a focal point that people study.The focal point of this paper is discussion the pressing-sintering arts and crafts of high temperature porcelain base phase change composite material. We select magnesium (MgO) and alumina (Al₂O₃) as base material, sodium carbonate ( Na₂CO₃) the sodium sulfate( Na₂SO₄ ) ,sodium chloride ( NaCl) and aluminum (Al)as phase change materials. Have discussed respectively the influence factors of pressing process and sintering process, we get the optimization pressing-sintering craft, have analyzed the sintering body property. The material can be satisfied with the mechanics requirement as filling materials. The optimum process is the following: mixing- grind fully - pressing- slowly warm up to 500℃- keep 12 hours - slowly cold to room temperature -control rate of rise temperature heat up to sintering temperature - keep a half hour - cool - sintering body.The aim of pressing is to get higher density and intact body. Because of alumina base powder is uneasy press, we chose glycerin to be plasticizer, yellow Vaseline is selected as lubricant to reduce the friction. According to the discrepancy of powder body determine pressing pressure, adopt relapse pressurization way. The press body's quality is intact and satisfied with the requirement of the process of later stage.Sintering is the last program of powder metallurgical produce. It is a crucial step because the reject that caused by sintering can not be saved through the following process. The sintering of this experiment is a liquid sintering course, the firing temperature is higher than the temperature of phase change point. Sintering atmosphere is general air atmosphere. In sintering, we discover, the powder body property, firing temperature, liquid quantity and additive, temperature control system etc, all these factors have great influence to sintering goods property.In the course of sintering there are weightlessness and pressing body. The shrinkage quantity more big the density more high, but devilishly shrinkage quantity is easy to cause the body form cracks. In the experiment, the shrinkage of magnesia base composite material is larger than alumina base material, therefore magnesia base composite material is easy to cause slight cracks in sintering course. Weightlessness has great influence to the product service life, for example, the composite material which uses sodium carbonate as material has serious weightlessness in the sintering, one of the important reasons is the volatilization and abruption of sodium carbonate in the high temperature, this certainly will lead the energy storage medium reduce gradually in the course of using it, consequently, the heat storage density and service life are all decrease. The stability sodium sulfate is better than sodium carbonate in high temperature, but its ability of heat storage is not as good as sodium carbonate, we should seek the more steady medium and its capacity of heat storage is excellent.Ceramics base phase change composite material is a kind of energy saving material, it has the advantage of large heat storage density and excellent property in high temperature than the ordinary heat storage material. Today, the country and enterprise pay more and more attention to energy saving, phase change heat storage material is a kind of environmental friendly new material, it has a fine application prospect. Should deepen the research to the material, such as its heat storage mechanism and produce technology.