CN107473749A - 一种莫来石基复相纤维及其制备方法 - Google Patents

一种莫来石基复相纤维及其制备方法 Download PDF

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CN107473749A
CN107473749A CN201710763027.XA CN201710763027A CN107473749A CN 107473749 A CN107473749 A CN 107473749A CN 201710763027 A CN201710763027 A CN 201710763027A CN 107473749 A CN107473749 A CN 107473749A
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mullite
fiber
complex phase
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aluminium
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张力
金雪
罗欢
周黎南
刘琳
李峻峰
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Chengdu Univeristy of Technology
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Abstract

本发明涉及一种莫来石基复相纤维及其制备方法,属于无机非金属材料领域。莫来石基复相纤维制备方法包括下列步骤:a、莫来石前驱体的制备;b、莫来石前驱体纺丝液的配置;c、莫来石凝胶纤维的纤维化成型;d、莫来石凝胶纤维在含氨气气氛中氮化;e、氮化纤维的稳定化热处理。本发明工艺过程简单,成本低廉,适合莫来石基复相纤维的批量生产;引入氮能构建多种晶相,晶相组成可调控,减小高温下莫来石晶粒快速长大问题,有利于纤维的高温力学性能。莫来石基复相纤维可用作金属基复合材料或陶瓷复合材料的增强体,以及高温隔热材料,满足高温长时间服役的需求。

Description

一种莫来石基复相纤维及其制备方法
技术领域
本发明涉及一种莫来石基复相纤维及其制备方法,属于无机非金属材料领域。本方法制备出的莫来石基复相纤维具有优良的耐热性和抗高温蠕变性能,可用于增强金属基或陶瓷基复合材料,在航空航天、汽车、能源等领域具有广泛的应用前景。
背景技术
莫来石纤维属于高性能陶瓷纤维的一种,以Al2O3-SiO2为主成分,有的还含有少量的添加剂如B2O3等。在Al2O3-SiO2体系中,莫来石是唯一的稳定化合物,具有高熔点(1842℃)、低热膨胀系数(3.5~4.4×10-6K-1)、低热导率(3~6W.m-1.K-1)和优良的抗高温蠕变性能等特点。莫来石还具有优良的高温力学性能,在1500℃还能保持90%的室温强度,非常适合用作高温结构陶瓷。
莫来石纤维可作为复合材料的增强体,也可用做高温隔热材料。当长期在高温环境(>1000℃)下应用时,莫来石晶粒快速生长导致其力学性能降低,是限制其在高温下应用的最主要因素。以美国明尼苏达矿业制造公司的Nextel 440和日本住友化学公司的Altex2K两种莫来石纤维为例,前者的平均晶粒尺寸在纳米范围(~80nm),强度为2.1GPa;后者晶粒达到亚微米(~115nm),强度只有1.25GPa。经1400℃热处理后,这两种纤维的强度都下降到1.1GPa,而此时晶粒都长大到~135nm(B.O.Hildmann,H.Schneider,M.Schmiicker.Hightemperature behaviour of polycrystalline aluminosilicate fibres with mullitebulk composition,I.Microstructure and strength properties.J.Eur.Ceram.Soc,1996,16:281-285)。因此,制备细晶莫来石纤维并抑制晶粒过快生长有利于提高其力学性能,提高其长期使用温度。
现有的莫来石纤维中,添加剂大多为B2O3,其作用是促进Al2O3-SiO2之间反应生成莫来石。美国专利US Patent 3,795,524公开了一种以硼酸为原料制备含B2O3的莫来石纤维,陶瓷纤维中B2O3和Al2O3的摩尔比为2/9~1/2。由于B2O3在晶界处形成玻璃相,降低纤维的抗蠕变性能,同时加速莫来石晶粒长大,强度也因此下降。此外,B2O3在高温下(>1000℃)容易挥发,也会造成纤维收缩和性能恶化。除B2O3外,莫来石其它的添加剂还有P2O5、TiO2等。它们虽然在一定程度上促进了莫来石的形成,但在高温下产生类似B2O3的负面影响,如形成了玻璃液相以及造成莫来石晶粒异常晶粒长大等。
因此,抑制莫来石晶粒粗化并避免引入玻璃相,是改善莫来石纤维的高温力学性能的关键。为了解决上述问题,本发明提供了一种莫来石基复相纤维及其制备方法。
发明内容
本发明要解决的技术问题在于提供一种莫来石基复相纤维的制备方法,莫来石纤维中的晶相组成可调控,减小高温下莫来石晶粒快速长大问题。
本发明的特征在于:是通过将含有铝、硅元素的莫来石前驱体纤维在含氨气气氛中煅烧,得到莫来石基复相纤维。
本发明所述的莫来石基复相纤维制备方法包括下列步骤:a、莫来石前驱体的制备;b、莫来石前驱体纺丝液的配置;c、莫来石凝胶纤维的纤维化成型;d、莫来石凝胶纤维在含氨气气氛中氮化;e、氮化纤维的稳定化热处理。
a步骤中,所述的莫来石前驱体可以通过分别制备氧化铝溶胶和二氧化硅溶胶,再将两种溶胶混合得到;也可以将含铝和含硅的有机醇盐(酯)混合后水解反应合成。
a步骤中,所述的氧化铝溶胶可以用金属铝和氯化铝反应制备,也可以用铝的有机醇盐水解制备。
a步骤中,所述的二氧化硅溶胶可以通过水玻璃经阳离子交换技术制备,也可以用有机硅酸酯经水解获得;二氧化硅溶胶与氧化铝溶胶混合前通常需要用酸调节pH值为酸性,以避免絮凝。
a步骤中,含铝的有机醇盐包括但不限于乙醇铝、丙醇铝、异丙醇铝、丁醇铝、仲丁醇铝等铝醇盐中的一种或几种;含硅的有机醇酯包括但不限于硅酸甲酯、硅酸乙酯、硅酸丙酯、硅酸丁酯等有机硅酸酯的一种或几种;将有机醇盐和有机硅酸酯混合溶解在低级醇中,加入酸性水溶液水解,得到莫来石前驱体。
a步骤中,莫来石前驱体的铝硅质量比满足氧化铝:二氧化硅=70~85:30~15,优选为72~80:28~20。
b步骤中,莫来石前驱体纺丝液的配置是在莫来石前驱体中加入纺丝助剂,经过搅拌均匀化处理,减压浓缩得到一定粘度的纺丝液体;纺丝助剂包括聚乙烯醇、聚氧化乙烯、聚乙二醇、聚乙烯吡咯烷酮中的一种或者几种,加入量为莫来石质量分数的0.1~20%。
c步骤中,莫来石凝胶纤维的纤维化成型是将一定粘度的莫来石前驱体纺丝液用高压气流喷吹或高速离心甩丝的办法获得凝胶纤维棉,也可以用干法纺丝的办法获得连续凝胶纤维;莫来石前驱体纺丝液的粘度为0.1Pa.s~1000Pa.s,根据成纤方法的要求而调整。
d步骤中,氮化气氛采用氨气和氮气/氩气/氢气等不含氧的气氛中的一种或几种混合,混合气体流量0.1~10L/min,氨气的体积分数10%~100%。氮化温度800~1400℃,升温速率1~10℃/min,保温1~5h。加热过程中莫来石前驱体发生热解,脱除水、二氧化碳等气体,并与氨气发生反应,部分氮原子取代Si-O或者Al-O上的氧原子,得到含氮的陶瓷纤维。
e步骤中,根据需要,氮化后的陶瓷纤维可在1200~1600℃进行稳定化热处理,升温速率1~100℃/min,保温1min~4h,气氛采用氮气或氩气中的一种或几种混合气氛,得到莫来石基复相纤维。
一种莫来石基复相纤维,采用上述方法制备得到,纤维中的氮含量1~15wt%,晶相组成为莫来石、氧化铝以及SiAlON中的两种或多种,晶粒细小,高温下晶粒生长速度低,纤维强度高,可用于金属基复合材料或陶瓷复合材料的增强体,也可以用于高温隔热材料,满足高温长时间服役的需求。
本发明所涉及莫来石基复相纤维及其制备方法,相比现有技术具有如下有益效果:
(1)在莫来石纤维中引入氮,构建多种晶相,抑制莫来石的晶粒生长速度,得到细晶组织,有利于纤维的高温力学性能;
(2)通过调整铝、硅以及氮含量,可对纤维的晶相组成和微观结构进行设计,获得所需要的性能,拓宽了纤维的应用范围。
(3)成本低廉,工艺过程简单,适合批量生产。
附图说明
图1是实施例1中氨气气氛煅烧所得莫来石基复相纤维的X射线衍射图;
图2是实施例1中空气气氛煅烧所得莫来石复相纤维的X射线衍射图;
图3是实施例2中氨气气氛煅烧所得莫来石基复相纤维的X射线衍射图;
图4是实施例2中空气气氛煅烧所得莫来石复相纤维的X射线衍射图;
图5是实施例3中所得含氮陶瓷纤维的X射线衍射图;
图6是实施例4中氮气气氛煅烧所得莫来石复相纤维的X射线衍射图;
图7是实施例5中所得莫来石复相纤维的扫描了电子显微镜图。
具体实施方式
本发明莫来石基复相纤维的制备方法,包括以下步骤:a、莫来石前驱体的制备;b、莫来石前驱体纺丝液的配置;c、莫来石凝胶纤维的纤维化成型;d、莫来石凝胶纤维在含氨气气氛中氮化;e、氮化纤维的稳定化热处理。
a步骤中,所述的莫来石前驱体可以通过分别制备氧化铝溶胶和二氧化硅溶胶,再将两种溶胶混合得到;也可以将含铝和含硅的有机醇盐(酯)混合后水解反应合成。
a步骤中,所述的氧化铝溶胶可以用金属铝和氯化铝反应制备,也可以用铝的有机醇盐水解制备。
a步骤中,所述的二氧化硅溶胶可以通过水玻璃经阳离子交换技术制备,也可以用有机硅酸酯经水解获得;二氧化硅溶胶与氧化铝溶胶混合前通常需要用酸调节pH值为酸性,以避免絮凝。
a步骤中,含铝的有机醇盐包括但不限于乙醇铝、丙醇铝、异丙醇铝、丁醇铝、仲丁醇铝等铝醇盐中的一种或几种;含硅的有机醇酯包括但不限于硅酸甲酯、硅酸乙酯、硅酸丙酯、硅酸丁酯等有机硅酸酯的一种或几种;将有机醇盐和有机硅酸酯混合溶解在低级醇中,加入酸性水溶液水解,得到莫来石前驱体。
a步骤中,莫来石前驱体的铝硅质量比满足氧化铝:二氧化硅=70~85:30~15,优选为72~80:28~20。
b步骤中,莫来石前驱体纺丝液的配置是在莫来石前驱体中加入纺丝助剂,经过搅拌均匀化处理,减压浓缩得到一定粘度的纺丝液体;纺丝助剂包括聚乙烯醇、聚氧化乙烯、聚乙二醇、聚乙烯吡咯烷酮中的一种或者几种,加入量为莫来石质量分数的0.1~20%。
c步骤中,莫来石凝胶纤维的纤维化成型是将一定粘度的莫来石前驱体纺丝液用高压气流喷吹或高速离心甩丝的办法获得凝胶纤维棉,也可以用干法纺丝的办法获得连续凝胶纤维;莫来石前驱体纺丝液的粘度为0.1Pa.s~1000Pa.s,根据成纤方法的要求而调整。
d步骤中,氮化气氛采用氨气和氮气/氩气/氢气等不含氧的气氛中的一种或几种混合,混合气体流量0.1~10L/min,氨气的体积分数10%~100%。氮化温度800~1400℃,升温速率1~10℃/min,保温1~5h。加热过程中莫来石前驱体发生热解,脱除水、二氧化碳等气体,并与氨气发生反应,部分氮原子取代Si-O或者Al-O上的氧原子,得到含氮的陶瓷纤维。
e步骤中,根据需要,氮化后的陶瓷纤维可在1200~1600℃进行稳定化热处理,升温速率1~100℃/min,保温1min~4h,气氛采用氮气或氩气中的一种或几种混合气氛,得到莫来石基复相纤维。
一种莫来石基复相纤维,采用上述方法制备得到,纤维中的氮含量1~15wt%,晶相组成为莫来石、氧化铝以及SiAlON中的两种或多种,晶粒细小,高温下晶粒生长速度低,纤维强度高,可用于金属基复合材料或陶瓷复合材料的增强体,也可以用于高温隔热材料,满足高温长时间服役的需求。
下面结合实施例对本发明的具体实施方式做进一步的描述,并不因此将本发明限制在所述的实施例范围之中。
实施例1
氧化铝溶胶用金属铝和三氯化铝反应制备。金属铝粉27g和结晶氯化铝48.2g投入1000ml圆底烧瓶,加入蒸馏水250g,回流10~12h,待铝粉溶解完全后,过滤获得澄清透明的氧化铝溶胶。加入由水玻璃经离子交换树脂得到的酸性硅溶胶(二氧化硅含量为20%,pH用盐酸调整为2)54g,混合均匀后再加入1g聚乙烯醇1788溶解后,减压浓缩至粘度达到20~50Pa.s,用干法纺丝机纺丝,纺丝速率100m/min,获得连续莫来石前驱体凝胶纤维。其氧化铝和二氧化硅的质量比为85:15。经60℃干燥12h,送入管式气氛炉。抽真空通氮气排除空气3次,通入氨气10L/min,以5℃/min速率升温至1200℃,保温3h,随炉降温,得到莫来石基复相纤维。经测量,所得的纤维平均直径为10μm,氮含量2.75%。X射线衍射分析结果见附图1,结晶相由莫来石、氧化铝和SiAlON的微小晶粒组成,晶粒尺寸分别为19nm、13nm和46nm,强度为2.4GPa。将莫来石基复相纤维在1300℃保温1h,莫来石晶粒长大为22nm。作为对比,将莫来石前驱体凝胶纤维在空气中以5℃/min速率升温至1200℃,保温3h,随炉降温,得到莫来石纤维。X射线衍射分析结果见附图2,结晶相为莫来石和氧化铝,其晶粒尺寸分别为65nm和17nm,强度为1.8GPa。将此莫来石纤维在1300℃保温1h,莫来石晶粒长大为148nm。
实施例2
称取异丙醇铝20.42g,加入到无水乙醇100g中溶解,然后加入pH为3.5的水溶液(醋酸调节)10g,搅拌反应4h得到氧化铝溶胶。正硅酸乙酯7.59g,加入到无水乙醇40g中,再加入pH为3.5的醋酸水溶液1.5g,室温水解1h,得到二氧化硅溶胶。将此二氧化硅溶胶倒入氧化铝溶胶混合均匀后,再加入15%的聚乙烯吡咯烷酮乙醇溶液10g,减压浓缩至粘度5~10Pa.s,用离心甩丝机甩丝,转速10000转/分钟,获得莫来石前驱体纤维棉。其氧化铝和二氧化硅的质量比为70:30。送入管式气氛炉,抽真空通氮气排除空气3次后,通入氨气0.1L/min,以5℃/min速率升温至1300℃,保温1h,随炉降温,得到莫来石基复相纤维。经测量,所得的纤维氮含量1.83%。X射线衍射分析结果见附图3,结晶相由莫来石、氧化铝和SiAlON的微小晶粒组成,晶粒尺寸分别为34nm、20nm和25nm,强度为2.3GPa。将莫来石基复相纤维在1250℃保温4h,莫来石晶粒长大为42nm。作为对比,将莫来石前驱体凝胶纤维在空气中以5℃/min速率升温至1300℃,保温1h,随炉降温,得到莫来石纤维。X射线衍射分析结果见附图4,结晶相只有莫来石,其晶粒尺寸130nm,强度为1.2GPa。将此莫来石纤维在1250℃保温4h,莫来石晶粒长大为280nm。
实施例3
称取仲丁醇铝24.6g,正硅酸甲酯3.24g,溶解在无水乙醇60g中,得到铝、硅混合溶液。搅拌下逐滴加入到pH为2.0的水溶液(醋酸调节)4g,让铝、硅的醇盐同时水解,反应4h得到莫来石前驱体溶胶,其氧化铝和二氧化硅的质量比为80:20。再加入10%的聚乙烯吡咯烷酮乙醇溶液10g,减压浓缩至粘度15~20Pa.s,用0.3MPa压力的高压气体通过纤维喷吹机将纺丝液喷入40℃的空气环境,获得莫来石前驱体纤维棉。送入管式气氛炉,抽真空通氮气排除空气3次后,通入氨气0.4L/min,以5℃/min速率升温至900℃,保温3h,随炉降温,得到含氮的陶瓷纤维。经测量,纤维氮含量为5.65%。X射线衍射分析结果见附图5,由氧化铝和含氮非晶相组成。
实施例4
将实施例3所得的含氮的陶瓷纤维在氮气气氛中经1250℃热处理30min,得到莫来石基复相纤维。X射线衍射分析结果见附图6,结晶相经X射线衍射证实由莫来石、氧化铝和SiAlON的微小晶粒组成,晶粒尺寸分别为12nm、26nm和43nm,强度2.7GPa。
实施例5
氧化铝溶胶的制备同实施例1。硅酸甲酯19.88g加入甲醇80ml和pH=2的盐酸水溶液20g,水解1h加入氧化铝溶胶。搅拌均匀,加入聚乙烯吡咯烷酮4g溶解后,减压浓缩至粘度达到30~60Pa.s,用干法纺丝机纺丝,纺丝速率150m/min,获得连续莫来石前驱体纤维。其氧化铝和二氧化硅的质量比为85:15。经60℃干燥4h,送入管式气氛炉。抽真空通氮气排除空气3次后,通入氨气流量1.2L/min,以1℃/min速率升温至1000℃,保温5h,随炉降温,得到含氮的陶瓷纤维。再在氩气气氛中经1300℃热处理30min,得到莫来石基复相纤维。经测量,所得的纤维氮含量6.23%。结晶相经X射线衍射证实由氧化铝和SiAlON的微小晶粒组成,晶粒尺寸分别为33nm和45nm,强度2.2GPa。纤维的SEM照片见附图7。
表1是实施例6~14中莫来石前驱体纤维的热处理条件及相应的氮含量和结晶相。
表1
以上列举的仅是针对本发明的可行性实施方式的若干个具体实施例说明,并非用来限制本发明的保护范围。显然,本发明不限于以上实施例。本领域的相关技术人员,通过对本发明的技术方法进行修改或者等同替代,而不脱离本发明技术方案的原理、形状、构造、特征、精神等变化与修饰,均应包含在本发明的权利要求范围之中。

Claims (13)

1.一种莫来石基复相纤维及其制备方法,其特征在于:是通过将含有铝、硅元素的莫来石前驱体纤维在含氨气气氛中煅烧,得到莫来石基复相纤维。
2.一种莫来石基复相纤维及其制备方法,其特征在于:包括以下步骤:a、莫来石前驱体的制备;b、莫来石前驱体纺丝液的配置;c、莫来石凝胶纤维的纤维化成型;d、莫来石凝胶纤维在含氨气气氛中氮化;e、氮化纤维的稳定化热处理。
3.根据权利要求1或2所述的莫来石基复相纤维的制备方法,其特征在于:a步骤中,所述的莫来石前驱体可以通过分别制备氧化铝溶胶和二氧化硅溶胶,再将两种溶胶混合得到;也可以将含铝和含硅的有机醇盐(酯)混合后水解反应合成。
4.根据权利要求1或2所述的莫来石基复相纤维的制备方法,其特征在于:a步骤中,所述的氧化铝溶胶可以用金属铝和氯化铝反应制备,也可以用铝的有机醇盐水解制备。
5.根据权利要求1或2所述的莫来石基复相纤维的制备方法,其特征在于a步骤中,所述的二氧化硅溶胶可以通过水玻璃经阳离子交换技术制备,也可以用有机硅酸酯经水解获得;二氧化硅溶胶与氧化铝溶胶混合前通常需要用酸调节pH值为酸性,以避免絮凝。
6.根据权利要求1或2所述的莫来石基复相纤维的制备方法,其特征在于:a步骤中,含铝的有机醇盐包括但不限于乙醇铝、丙醇铝、异丙醇铝、丁醇铝、仲丁醇铝等铝醇盐中的一种或几种;含硅的有机醇酯包括但不限于硅酸甲酯、硅酸乙酯、硅酸丙酯、硅酸丁酯等有机硅酸酯的一种或几种;将有机醇盐和有机硅酸酯混合溶解在低级醇中,加入酸性水溶液水解,得到莫来石前驱体。
7.根据权利要求1或2所述的莫来石基复相纤维的制备方法,其特征在于:a步骤中,莫来石前驱体的铝硅质量比满足氧化铝:二氧化硅=70~85:30~15,优选为72~80:28~20。
8.根据权利要求1或2所述的莫来石基复相纤维的制备方法,其特征在于:b步骤中,莫来石前驱体纺丝液的配置是在莫来石前驱体中加入纺丝助剂,经过搅拌均匀化处理,减压浓缩得到一定粘度的纺丝液体;纺丝助剂包括聚乙烯醇、聚氧化乙烯、聚乙二醇、聚乙烯吡咯烷酮中的一种或者几种,加入量为莫来石质量分数的0.1~20%。
9.根据权利要求1或2所述的莫来石基复相纤维的制备方法,其特征在于:c步骤中,莫来石凝胶纤维的纤维化成型是将一定粘度的莫来石前驱体纺丝液用高压气流喷吹或高速离心甩丝的办法获得凝胶纤维棉,也可以用干法纺丝的办法获得连续凝胶纤维;莫来石前驱体纺丝液的粘度为0.1Pa.s~1000Pa.s,根据成纤方法的要求而调整。
10.根据权利要求1或2所述的莫来石基复相纤维的制备方法,其特征在于:d步骤中,氮化气氛采用氨气和氮气/氩气/氢气等不含氧的气氛中的一种或几种混合,混合气体流量0.1~10L/min,氨气的体积分数10%~100%;氮化温度800~1400oC,升温速率1~10oC/min,保温1~5h;加热过程中莫来石前驱体发生热解,脱除水、二氧化碳等气体,并与氨气发生反应,部分氮原子取代Si-O或者Al-O上的氧原子,得到含氮的陶瓷纤维。
11.根据权利要求1或2所述的莫来石基复相纤维的制备方法,其特征在于:e步骤中,根据需要,氮化后的陶瓷纤维可在1200~1600oC进行稳定化热处理,升温速率1~100oC/min,保温1min~4h,气氛采用氮气或氩气中的一种或几种混合气氛,得到莫来石基复相纤维。
12.一种莫来石基复相纤维,其特征在于:所述莫来石基复相纤维采用权利要求1~11任一项所述的方法制备得到。
13.一种莫来石基复相纤维,其特征在于:纤维中的氮含量1~15wt%,晶相组成为莫来石、氧化铝以及SiAlON中的两种或多种,晶粒细小,高温下晶粒生长速度低,纤维强度高,可用于金属基复合材料或陶瓷复合材料的增强体,也可以用于高温隔热材料,满足高温长时间服役的需求。
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CN110117841A (zh) * 2019-05-13 2019-08-13 天津大学 一种电纺双相前驱体制备莫来石纳米纤维的方法
CN112481718A (zh) * 2020-11-25 2021-03-12 浙江炜烨晶体纤维有限公司 一种多晶莫来石纤维甩丝机
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CN110117841A (zh) * 2019-05-13 2019-08-13 天津大学 一种电纺双相前驱体制备莫来石纳米纤维的方法
CN110117841B (zh) * 2019-05-13 2021-11-23 天津大学 一种电纺双相前驱体制备莫来石纳米纤维的方法
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Application publication date: 20171215