Na^+对制备Al_4SiC_4/Al_4O_4C复合耐火材料的影响

以焦宝石、活性炭和铝粉为原料,添加Na2CO3制备Al4SiC4/Al4O4C复合耐火材料。采用化学分析、XRD和SEM等测试技术,研究了Na+对材料物相组成和显微结构的影响。结果表明:添加Na2CO3加速了Al2O3和活性炭的反应,促进了Al4O4C的生成。未添加Na2CO3时生成的Al4SiC4晶粒表面光滑,添加Na2CO3后Al4SiC4晶粒粗糙、凹凸,缺陷明显增加。此外,未添加Na2CO3的试样中生成的Al4O4C呈短纤维状,添加Na2CO3后全部转变为细小颗粒。

铝对高岭石熟料合成Al_4SiC_4-Al_4O_4C复合材料的影响

将高岭石熟料粉、炭黑粉和金属铝粉按n（Al2O3）：n（C）：n（A1）：1：6．5：2．6配料作为基料，保持高岭石熟料粉和炭黑的量不变，改变金属铝粉的量，使n（A1）从2．6分别增加到3．9、5．5、7．0、8．6和10．4，以酚醛树脂为结合剂，无水酒精为分散剂，混匀后压制成型，坯体试样干燥后，在刚玉质管式炉内，氩气气氛下，于1700℃保温2h制备了Al4SiC4-Al4O4C复合材料。利用DTA—TG、XRD和SEM等测试技术，研究了铝粉加入量对该材料相组成和显微结构的影响。结果表明：在一定范围内随着金属Al粉加入量的增加，Al4SiC4产物的含量也会相应的增加。试样中生成的Al4SiC4有片状和块状两种形貌，粒径分别在5～15和10～20μm之间。金属Al粉添加量的增加，对Al4SiC4晶粒形状和粒径影响不大；合成的Al4SiC4粒径一般在1μm以下，主要分布在Al4SiC4晶粒表面，形状无规则，部分还粘结在一起。

TiO_2对制备Al_4SiC_4-Al_4O_4C复合材料的作用

将焦宝石粉、活性炭粉和铝粉按质量比39:27.6:33.4配料作为基料,再分别加入占基料总质量0、3%、6%和9%的TiO2粉末(锐钛矿型),加入<10%的酚醛树脂为结合剂混匀后,压制成型,坯体试样干燥后,置于刚玉管式炉中,通入流动氩气,分别于1300、1400、1500、1600和1700℃保温2h制备了Al4SiC4-Al4O4C复合材料。利用热重分析、化学分析、XRD和SEM等测试技术,研究了TiO2加入量对材料物相组成和显微结构的影响。结果表明:试样中的Ti在烧成过程中有少量损失,残余的TiO2在1300℃前全部反应转变为TiC,生成的TiC在1300～1700℃稳定存在;TiO2加入量对材料物相组成没有明显影响,但TiO2加入量超过3%时,Al4SiC4和Al4O4C的生成温度将由1500℃提升至1600℃;随着材料中Ti4+浓度增加,Ti4+更容易与Al4SiC4形成有限置换固溶体而导致晶格缺陷,促使Al4SiC4在1700℃分解,形成更多的Al4O4C短纤维,同时使试样表面生成片状Al2O3层。

Effect of Al on Al_4SiC_4-Al_4O_4C Composite Synthesized from Kaolinite Grog

The Al4SiC4 - Al4 O4 C composites were synthesized using 1： 6. 5：2.6 of nudar rntio of kaolinite grog powder, carbon black, and aluminum powder as basic formulation, fixing the additions f kaolinite grog powder and carbon black, vauing aluminum powder addition to make its proportion from 2. 6 to 3. 9, 5. 5, 7. 0, 8. 6, and 10. 4, respectively, adding phenolic resin as binder and absolute alcohol as dispersant, m＆ing well, pressing, drying, and firing at 1 700 for 2 h in a corundum tubularfizrnace in flowing argon. The eeffect cf Al addition on phase tvmposition and mierostrture of Al4SiC4 - Al4 O4 C composites wgs investigated by DTA - TG , XRD , and SEM. The results show that：（1 ） in a certain degree, more Al4SiC4 - Al4 O4 C forms with Al powder addition increasing; （2） the formed Al4SiC4 - Al4 O4 C two morphologies, narrwly, sheet atul block, atul their panicle sizes are. 5 - 15 n and 10 -20 p.m , respectively; （3） the A1 powder htition increase ha.s little effect on the grain shape and size of Al4SiC4 - Al4 O4 C： （4） ttw formed Al4O4C mainly distributes on ttw surfctce of the AluSiC4 grains with irregular shape atut partitle size below I p,m, and some of them bond together.

Effect of TiO_2 on Synthesis of Al_4SiC_4/Al_4O_4C Composite

Al4SiC4/Al4O4C composites were synthesized based on m （ sintered clay） ： m （ active carbon ） ： m （ aluminum powder） =39： 27. 6： 33. 4, adding TiO2 powder （ anatase type, 0. 3%, 6%, 9%, respectively）, adding 〈 10% phenolic resin as binder, mixing well, pressing, drying, firing in a corundum tubular furnace in flowing argon at 1 300, 1 400, 1 500, 1 600 and 1 700℃ for 2 h, respectively. Effect of TiO2 addition on phase composition and microstructure of Al4SiC4/Al4O4C composites was investigated by TGA, chemical analysis, XRD and SEM. The results show that ： （ 1 ） Ti in the specimens loses a little in the process of firing, all residual TiO2 transforms into TiC when the firing temperature is below 1 300℃, and the formed TiC exists stably at 1 300 - 1 700 ℃; （2） the TiO2 addition has little effect on phase composition of composites ; however, when more than 3% of TiO2 is added, the formation temperature of Al4SiC4 and Al4O4C increases from 1 500 ℃ to 1 600℃ ; （ 3 ） with the concentration of Ti^4＋ increasing, Ti^4＋ may react easily with Al4SiC4 and Al4O4C forrning the finite substitution solid solution resulting in lattice defect, which leads to the decomposition of Al4SiC4 at 1 700℃, the formation of more Al4O4C short fiber, and the formation of flake Al2O3 layer on suorface of the specimen.