干熄焦炉用原位生成AlN晶须增强莫来石-碳化硅质耐火材料

为了提高干熄焦炉斜道支柱用耐火材料的强度与韧性,在莫来石-碳化硅耐火砖中引入不同量的Al粉(其质量分数分别为2%、4%、6%和8%),并研究了Al粉粒径(中位粒径分别为74、38和13 μm)、氮化温度(600、850、1 000和1 200 ℃)及催化剂(分别为纳米Fe粉与氮化硅铁,外加质量分数均为0.5%)对其在氮气气氛下烧成后结构与性能的影响。结果表明:随着Al粉加入量的增加,试样的高温抗折强度逐步提高,Al粉的加入量( w )为6%时,其高温抗折强度可达41.3 MPa,是普通莫来石-碳化硅耐火砖的3倍以上;在5 MPa载荷作用下,经7次循环后,1 400 ℃时普通莫来石-碳化硅耐火砖试样发生断裂,而添加Al粉的试样在18 MPa载荷作用下还可继续承受载荷循环作用;升温至800 ℃左右,材料中的Al与N 2反应生成AlN,继续升高温度或延长保温时间,生成了AlN晶须;添加微量的纳米Fe粉催化剂,600 ℃氮化气氛处理后即生成了AlN,850 ℃形成了AlN晶须,从而使试样的强度和韧性显著提高。综合考虑各项性能,Al粉的适合加入量为6%( w ),最佳Al粉的中位粒径为38 μm,最佳催化剂为纳米Fe,其对应的最佳氮化温度为850 ℃。

Mullite-silicon carbide refractory materials strengthened by in-situ generated AlN crystal whiskers for dry quenching coke furnace

In order to improve the strength and toughness of refractories for the ramp pillar of dry quenching coke furnaces,different amounts of Al powder (2%,4%,6%,and 8%,by mass) were added into mullite - silicon carbide refractory bricks,and the effects of the particle size of Al powder (median particle size of 74,38 and 13 μm),nitriding temperature (600,850,1 000 and 1 200 ℃) and catalyst (nano-Fe powder and ferrosilicon nitride,extra-adding 0.5,by mass) on the structure and properties of the specimens fired in nitrogen atmosphere were studied.The results show that,with the increase of the addition of Al powder,the hot modulus of rupture of the specimens gradually increases,and when the addition of Al powder is 6%,the HMOR reaches 41.3 MPa,which is more than 3 times of that of the ordinary mullite - silicon carbide refractory brick;the specimen of ordinary mullite - silicon carbide refractory brick fractures at 1 400 ℃ under 5 MPa after 7 cycles,while the specimen with Al powder can continue the test after 7 cycles under 18 MPa;when the temperature rises to about 800 ℃,Al in the material and N 2 react to form AlN,afterwards AlN whiskers are generated with the increasing temperature or the prolonging duration;adding a trace amount of nano-Fe powder catalyst,AlN is generated after nitriding at 600 ℃,and AlN whiskers are formed at 850 ℃,which significantly improve the strength and toughness of the specimen.Generally,the suitable conditions are 6% Al powder, 38 μm median particle size of Al powder,nano-Fe powder,and 850 ℃ of nitriding temperature.