In pursuit of high thermal conductivity of SiC ceramics, this article reports the effects of AlN and sintering atmospheres on the thermal properties and microstructure evolution of SiC ceramics. Dense SiC ceramics with different contents of AlN additive were fabricated through hot-press sintering at 1950°C in Ar/N₂ atmosphere under a pressure of 40 MPa for 3 h. The results showed that the thermal conductivity of samples without AlN addition was 53.5 W.m⁻¹.K⁻¹ when sintered in Ar and 50.3 W.m⁻¹.K⁻¹ when sintered in N₂. The SiC ceramics with 4 wt% AlN sintered in Ar showed abnormally large grains and exhibited the highest thermal conductivity of 121.7 W.m⁻¹.K⁻¹ among all the samples. The sample with 2 wt% AlN sintered in N₂ exhibited a thermal conductivity of 108.6 W.m⁻¹.K⁻¹; the thermal conductivity deceased with the increasing AlN content afterwards. Such a decreasing trend of thermal conductivity was attributed to the ascending 2H_ss content and smaller grains of ceramics. There existed an optimal content of AlN and a proper sintering atmosphere for perfecting the microstructure and the thermal conductivity of SiC ceramics.

为了追求 SiC 陶瓷的高导热性，本文报道了 AlN 和烧结气氛对 SiC 陶瓷的热性能和微观结构演变的影响。通过在 1950°C、Ar/N ₂气氛、40 MPa 压力下热压烧结3 h制备了具有不同 AlN 添加剂含量的致密 SiC 陶瓷。结果表明，未添加AlN 的样品在Ar 中烧结时的热导率为53.5 Wm ^-1 .K ^-1，在N _{2 中}烧结时为50.3 Wm ^-1 .K ^-1。在 Ar 中烧结的具有 4 wt% AlN 的 SiC 陶瓷显示出异常大的晶粒，并表现出最高的热导率 121.7 Wm ^-1 .K^-1在所有样本中。具有在 N _{2 中}烧结的 2 wt% AlN 的样品表现出 108.6 Wm ^-1 .K ^-1的热导率；之后随着 AlN 含量的增加，热导率下降。这种热导率的下降趋势归因于 2H _ss含量的增加和陶瓷颗粒的变小。存在最佳的AlN含量和合适的烧结气氛，以完善SiC陶瓷的微观结构和热导率。