Ceramic powder sintering atmosphere
Ceramic powder sintering atmosphere refers to the condition of the environment in which the powder sintering process is performed. The most important factor of the powder sintering atmosphere is the nitrogen content. Nitrogen affects the sinterability and structure of the powder. As the sintering temperature increases, the nitrogen content has a great influence on the diffusivity and solubility of solid components.
Ceramic powder sintering atmosphere is composed of multiple components, such as, gas, liquid and powder components. The gas component includes nitrogen, oxygen, hydrogen, carbon dioxide and other gases. The liquid component is usually a liquid containing acid or base agents, such as water and alcohols. The powdercomponent may be a solid material such as ceramic powders.
Ceramic powder sintering atmosphere can often be classified as reducing atmosphere, normal atmosphere and oxidizing atmosphere, based on the concentrations of the gases. A reducing atmosphere has more nitrogen and lower concentrations of oxygen, hydrogen and carbon dioxide; an oxidizing atmosphere has higher concentrations of oxygen and/or carbon dioxide; and a normal atmosphere has equal parts of oxygen, nitrogen, hydrogen and carbon dioxide.
The choice of ceramic powder sintering atmosphere highly depends on the type of powder and what kind of sintering process is to be used. Generally, oxidizing atmospheres are used for low-temperature sintering processes, such as uniaxial compaction and slip casting. However, if certain oxide powders are to be sintered, nitrogen base atmospheres are used, and can reach temperatures up to 2600C. For high-temperature sintering processes, reducing atmospheres usually reach temperatures up to 1800C.
The primary goal of this sintering atmosphere is to obtain desired mechanical properties in the final parts, such as high strength and high wear-resistance. The main purpose of the atmosphere is to create a proper environmental condition and presence of oxygen to combust the ceramic powder. Proper controlling of parameters, such as temperature and pressure, of the ceramic powder sintering atmosphere ensures that the sintered parts have the desired properties.
Moreover, controlling of the atmosphere is especially important for binder burn off, which is a crucial step in sintering process. The sintering atmosphere also affects the self-diffusion process, which can be beneficial in the final part. The rate of self-diffusion increases with an increasing temperature.
In conclusion, the ceramic powder sintering atmosphere has an important role in the sintering process of ceramic powders. The atmosphere can affect the physical properties and mechanical properties of sintered parts, depending on what type of atmospheric condition is used. Different atmospheres are used for different types of ceramic powders and/or sintering processes, and the atmosphere can be changed depending on what type of final parts are desired. Proper controlling and management of the atmosphere during the sintering process ensures that the final parts have the desired properties.
