Preparation, Structure And Properties Of Diatomite-based Humidity Buffering Materials

The humidity condition in residential building has effect on human health directly. At present, air conditioner has been widely used to regulate the humidity, but it is not good for environment and energy conservation. Therefore, humidity buffering materials which can control humidity passively have become the focus of the fields in the aspect of humidity controlling technology. This kind of materials can keep the indoor humidity in a certain range by the process of water adsorption and desoption, so it should have peculiar properties and structure. Diatomite is a natural porous material and has lots of advantages such as high adsorption capacity, chemical stability, high specific surface area and so on. In addition, diatomite is abundant in our country. So the research of diatomite based humidity control materials is very important to both environment and energy saving.In this research, the basic material was determined after compared two kinds of diatomite and diatomite porous ceramics used as humidity control materials were successfully fabricated by pressure molding and sintering process. The influences of the preparation process on the properties of materials were discussed after analysised the characterazition of microstructure, mechanical property and humidity controlling behavior. The principle of humidity control process was further explained by the test of pore size distribution. The dynamic process of humidity controlling by diatomite porous ceramics is also disscussed. The main conclusions drawn in the thesis are as follows.1. A technique to fabricate diatomite porous ceramics which can control humidity itself is presented;2. The bending strength of diatomite porous ceramics can be enhanced when the sintering temperature increase or Na2SiO3 is added;3. The humidity controlling behavior of diatomite porous ceramics would decrease when the sintering temperature increase or starch and binder are added.4. The humidity controlling behavior of diatomite porous ceramics mainly rely on the physical adsorption in microporous and the capillary condensation in mesoporous.5. Through the transformation of the adsorption/desorption curves, it was found that the water adsorption process of porous bulk mateials is a diffusion process.6. The acid leaching process can improve the humidity controlling behavior of diatomite porous ceramics.