Preparation of new functional materials using low temperature densification by HIP

采用热等静压法低温烧结Fe_4N磁性材料和SiO_2非晶-晶态复合材料。1. Fe_4N的热等静压烧结将含Fe_4N粉末的密封胶囊在450-550 ℃、50- 200 MPa下热等静压2小时。在500 ℃、200 MPa热等静压处理下，试样的相对密度最大，达到97%。在450 ℃、200 MPa条件下获得的样品的最大饱和磁化强度为182 emu/g。为了获得低的涡流损耗和高的饱和磁化强度，还对Fe_4N和Fe的混合物进行了热等静压处理。当Fe_4N含量为96wt%时，热等静压处理后的Fe_4 N-Fe复合材料的电阻率为7.08 × 10 ~ <-5>4 Ω·cm，是纯铁的10倍。在Fe中加入70wt%Fe_4N，铁损可降至10 W以下，SiO_2非晶-晶态复合材料的热等静压烧结将α-石英和SiO_2玻璃的混合粉末压制成PHI 12 mm × 20 mm的压坯，将压坯装入Pyrex玻璃管中，在800-1200 ℃下热等静压30- 40 min。在50- 200 MPa的压力下240分钟。在120 ℃、100和200 MPa压力下，获得了具有天然玛瑙外观的试样。偏光显微镜观察表明，微晶位于非晶SiO_2基体中。当α-石英含量为25wt%时，在1200 ℃、200 MPa下保温120分钟，可获得最大密度为2.50g/cm^3的复合材料。在这种情况下，获得的最大抗弯强度为9.2Kg/mm ^2，相当于天然玛瑙的70%。

Fe_4N magnetic material and SiO_2 amorphous-crystalline composite were sinterd at low temperature by applying Hipping pressure. At high temperature, Fe_4N decomposes and amorphous SiO_2 with crystalline SiO_2 is crystallized.1.Hip sintering of Fe_4N The sealed capsule containing Fe_4N powder was hipped at 450-550ﾟC for 2 hours under 50-200Mpa. The maximum relative density 97% was obtained for the specimen hipped at 500ﾟC under 200MPa. THe maximum saturation magnetization 182emu/g was measured for a specimen obtained at 450ﾟC under 200MPa.The HIP technique was also applied to the mixture of Fe_4N and Fe, in order to obtain low eddy current loss and high saturation magnetization. The resistivity of hipped Fe4N-Fe composite with 96wt% Fe_4N was 7.08 * 10^<-5> OMEGAcm, which was ten times larger than that of iron. The iron loss was decreased to 10 W by the addition 70wt% of Fe_4N to Fe, compared with 19 W in pure iron.2.Hip sintering of SiO_2 amorphous -crystalline composite The mixed powder of alpha-quartz and SiO_2 glass was pressed into a compact with PHI 12mm * 20mm in size.The Pyrex glass capsule containing the compact was hipped at 800-1200ﾟC for 30-240 minutes under the pressure of 50-200MPa. Tne specimens with the appearance of natural agate : were obtained at 120ﾟC under 100 and 200MPa. The polarization microphotograph showed that the crystallites were in the amorphous SiO_2 matrix. Using the starting mixture with 25wt% of alpha-quartz, the maximum density of 2.50g/cm^3 was obtained at 1200ﾟC for 120 minutes under 200MPa. In this case, the maximum bending strength was obtained to be 9.2Kg/mm^2.corresponding to 70% of that in the natural agate.