The Study On Fabrication Of AIN Ceramics By Hot-press Sintering

Aluminum nitride ceramics with high temperature resistance,corrosion resistance,thermal conductivity,hardness and thermal stability have attracted much attention due to its potential as substrate material for microelectronics.The aluminum nitride ceramics manufacturing by the process of the tape casting and pressureless sintering process have been industrialized in China,but it is not suitable for the production of large and complex parts.The process of hot-press sintering aluminum nitride ceramic is relatively simple and suitable for the preparation of aluminum nitride block with certain thickness.In this paper,the optimum sintering process of sintering aluminum nitride ceramics was studied by using the commercial aluminum nitride powder in China.The influence of the particle size of yttrium oxide additive,the different content of additives,the sintering temperature of hot pressing sintering and the time of heat preservation on the density and thermal conductivity of AIN ceramic was studied.The effect of annealing time under nitrogen atmosphere on the properties of aluminum nitride ceramics was studied.At last,the processing technology of AIN ceramics was explored preliminary.The results of hot pressing sintering of aluminum nitride are shown that the density and thermal conductivity of aluminum nitride ceramics used in the preparation of yttrium oxide additives with particle size of 0.5-1 ?m are higher than that of the particle size of 1-3 ?m.All samples can be sinered to complete densification as the content of yttrium oxide with 0.5-1 ?m particle size is more than 0.125%,thermal conductivity of sample showing a downward trend after rising first.The density of the sample content 1.5%of additive did not change with the increase of sintering temperature,the thermal conductivity of the samples showed an upward trend.The relative density of the sample did not change with the increase of holding time,The thermal conductivity shows a trend of rising first and then decreasing.The result of AIN ceramic of hot pressing sintering with atmospheric heat treatment showed that the density of the sample with additive showed a downward trend,the AIN grain growed up,and the second phase of the aluminum nitride granule showed a decrease and then upon trend with the increase of heat treatment time.With the increase of additive content,the thermal conductivity of aluminum nitride ceramic under different heat treatment time showed a trend of increasing first and then decreasing.The thermal conductivity of AIN ceramic is highest when the additive content was 1.5%,the sintering temperature was 1820 ? and heat treatment time was 1.5 h.The results of the exploration of the processing technology' of AIN ceramics showed that 200 MPa isostatically pressed aluminum nitride blocks can be used for machining,boron nitride was used to separate aluminum nitride billets,and aluminum nitride ceramics prepared by hot-press sintering can be automatically separated.