将甩丝后得到的凝胶纤维分别以0.5、1、1.5、2、2.5、3和4 ℃·min-1的升温速率升温至400℃,保温1 h后再以3℃·min-1的升温速率升温至600℃并保温1 h进行中温热处理,然后分别置入1 000、1 100、1 200、1 300和1 400℃的电炉中保温1 h烧成.测试中、高温处理后纤维的平均单丝拉伸强度,并采用SEM观测纤维表面形态.结果表明:中温段(400 ℃以下)升温速率为0.5～1℃·min-1时,600 ℃处理后纤维的平均单丝拉伸强度>1 000 Mpa,此时于1 000～1 100℃烧成的纤维平均单丝拉伸强度可达800 Mpa以上,纤维表面平整光滑,于1 200℃烧成的纤维内部开始出现α-Al2O3,于1 300℃及以上温度烧成的纤维内部α-Al2O3大量出现;升温速率>3℃·min-1时,中温处理后纤维出现了较明显的粉化现象.%The swung gel fibers were heated to 4OO ℃ at 0 .5, 1,1. 5,2,2.5,3 ,and 4 ℃. min -1 of heating rate.respectively,and socked for 1 h;then heated to 6OO ℃ at 3 ℃ · min -1 of heating rate and socked for 1 h;at last calcined at 1 O00,1 100, 1 200,1 300. and 1 400 ℃ for 1 h. respectively. The average single fiber tensile strengthes of fibers after calcining at 600 ℃ or higher temperatures were determined and their surface morphology was observed. The results show that: ( 1 ) when the heating rate beow 40O ℃ is 0.5 - 1 ℃· min-1. the single fiber tensile strengthes after calcining at 600 ℃ and 1 00O - 1 100 ℃ exceed 1 00O and 8O0 MPa, respectively.the fiber surface after calcining at 100O - 1 100 ℃ is srnouth,α-Al2O3 begins to occur when calcining at 1 200 ℃,and a large amount of α-Al2O3 forms above 1 30O ℃;(2)when the heating rate is 3 ℃ · min -1 ,the fibers pulverize obviously.
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