CN108091758A - 一种钨铼热电偶抗氧化涂层结构中的氧阻挡材料及其应用 - Google Patents

一种钨铼热电偶抗氧化涂层结构中的氧阻挡材料及其应用 Download PDF

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CN108091758A
CN108091758A CN201711284789.8A CN201711284789A CN108091758A CN 108091758 A CN108091758 A CN 108091758A CN 201711284789 A CN201711284789 A CN 201711284789A CN 108091758 A CN108091758 A CN 108091758A
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陈实
邱新潮
徐健博
张博文
杨晓非
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Huazhong University of Science and Technology
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Abstract

本发明属于温度测量技术领域,涉及一种钨铼热电偶高温抗氧化涂层结构中的氧阻挡材料及其应用。该氧阻挡材料为多层结构,总厚度为50~200μm,该多层结构中的氧阻挡材料存在成分梯度和浓度梯度,即通过调整每一层材料种类或材料之间的配比,使得氧阻挡材料中各层材料热膨胀系数向远离钨铼热电偶基体的方向逐渐增大,氧阻挡材料中各层材料的耐氧烧蚀能力向远离钨铼热电偶基体的方向也逐渐增大,从而增加钨铼热电偶高温抗氧化涂层的附着力,同时减小钨铼热电偶高温抗氧化涂层的应力。

Description

一种钨铼热电偶抗氧化涂层结构中的氧阻挡材料及其应用
技术领域
本发明属于温度测量技术领域,更具体地,涉及一种钨铼热电偶高温抗氧化涂层结构中的氧阻挡材料及其应用。
背景技术
对于1600℃以上超高温度的测量,目前多采用非接触(红外、光学等)方法测量,但非接触方法不仅响应速度慢,而且测温精度远不如采用热电偶进行直接接触式测温。铂铑(Pt-Rh)热电偶、镍铬-镍硅热电偶、铁-康铜热电偶和钨铼(W-Re)热电偶是比较常见的几种高温热电偶,其中钨铼热电偶与其它热电偶相比,具有明显的优势:
(1)熔点高(>3000℃),强度大,抗热震性好,化学性质稳定;
(2)热电动势大(约为铂铑热电偶的2~3倍),灵敏度高;
(3)测温范围大,工作温度上限可达2800℃;
(4)价格便宜(约为铂铑热电偶的十分之一)。
然而,钨铼热电偶在有氧环境下从300℃左右即开始氧化,只适用于还原、惰性、真空等环境的高温测量,不能在高温氧化性气氛中应用。因此,如何提高钨铼热电偶抗氧化能力,一直是国内外高温测量领域高度关注的课题。
目前在有氧环境下使用钨铼热电偶测温,一般采取两种方式:一种是一次性测量使用,即每次测温时间很短,热电偶氧化失效后即不再使用或重新处理加工后使用,另一种方式是对热电偶采取抗氧化处理。目前商业化的钨铼热电偶防氧化技术主要为铠装保护法,即采用石英、刚玉、难熔金属以及高温陶瓷等作为保护管,装入钨铼热电偶后抽空密封、充惰性气体密封或充填惰性粉体密封,在保护管内为热电偶人为创造出非氧化性气氛,使其在氧化蚀损前完成测温使命,但这种不可拆卸的实体型抗氧化热电偶,存在以下问题:
(1)热电偶使用温度受保护管耐温能力的限制,通常低于1800℃;
(2)热电偶铠装保护后体积和重量增大,在体积要求比较严格的系统中使用受到限制;
(3)采用套管和填充物质保护后,热电偶的响应速度受到很大影响。
通过在钨铼热电偶表面涂覆抗氧化涂层,在不影响响应速度的前提下,提高热电偶在高温空气及其它高温氧化气氛中的测温上限、延长测温工作时间,是解决以上问题的比较理想的方法。实际上,国内外这方面的研究从上世纪六十年代起就已开展,但始终未见持续性的公开报道,而且全球范围内至今没有相关产品投入实际使用。
本发明提出了一种新型的用于钨铼热电偶表面的高温抗氧化氧阻挡材料,使之能实现2000℃以上超高温有氧环境下的长时间接触式测温。
发明内容
针对现有技术的以上缺陷或改进需求,本发明提供了一种钨铼热电偶高温抗氧化涂层结构中的氧阻挡材料及其应用,其目的在于通过在钨铼热电偶高温抗氧化涂层结构中的最外部设置一种多层结构的氧阻挡材料,该多层结构中的氧阻挡材料存在成分梯度和浓度梯度,即通过调整每一层材料种类或材料之间的配比,使得氧阻挡材料中各层材料热膨胀系数向远离钨铼热电偶基体的方向逐渐增大,氧阻挡材料中各层材料的耐氧烧蚀能力向远离钨铼热电偶基体的方向也逐渐增大,从而增加钨铼热电偶高温抗氧化涂层的附着力,同时减小钨铼热电偶高温抗氧化涂层的应力,由此解决2000℃以上超高温有氧环境中的长时间接触式测温的问题。
为实现上述目的,按照本发明的一个方面,提供了一种钨铼热电偶抗氧化涂层结构中的氧阻挡材料,其为不低于2层的多层结构,所述氧阻挡材料中各层材料的热膨胀系数向远离所述钨铼热电偶基体的方向逐渐增大。
优选地,所述多层结构的氧阻挡材料存在成分梯度或浓度梯度,即所述氧阻挡材料的多层结构中每一层采用不同的材料种类以形成成分梯度;或者每一层材料种类相同且至少为两种材料的混合物,但是各层中材料的配比不同以形成浓度梯度。
优选地,所述氧阻挡材料最外层的热膨胀系数与所述基体热膨胀系数之差的绝对值不大于7×10-6K-1
优选地,所述氧阻挡材料中各层材料的耐氧烧蚀能力向远离所述钨铼热电偶基体的方向逐渐增大。
优选地,所述氧阻挡材料选用在2000℃以上能起到氧阻挡或耐氧烧蚀作用的难熔金属氧化物、硼化物或氮化物。
优选地,所述氧阻挡材料选自氧化硅、氧化铪、硼化铪、氮化铪、氧化锆、硼化锆、氮化锆和氧化钇中的一种或多种。
优选地,所述氧阻挡材料总厚度为50~200微米。
优选地,所述氧阻挡材料的层数为5~20层。
按照本发明的另一个方面,提供了一种所述的钨铼热电偶抗氧化涂层结构的氧阻挡材料的应用,用作钨铼热电偶抗氧化涂层结构中的氧阻挡材料,该氧阻挡材料位于所述钨铼热电偶抗氧化涂层结构的最外部。
优选地,所述氧阻挡材料附着于所述钨铼热电偶基体表面。
优选地,通过化学气相沉积法、热喷涂法或溶胶凝胶法在所述钨铼热电偶基体表面制备得到所述氧阻挡材料。
总体而言,通过本发明所构思的以上技术方案与现有技术相比,能够取得下列有益效果:
(1)本发明提出的钨铼热电偶高温抗氧化涂层结构中包含有多层结构的氧阻挡材料,该多层结构中的氧阻挡材料存在成分梯度和浓度梯度,即通过调整每一层材料种类或材料之间的配比,使得形成的氧阻挡材料在靠近钨铼热电偶基体的氧阻挡层材料热膨胀系数与基体热膨胀系数之差的绝对值不大于7×10-6K-1,且氧阻挡材料中各层材料热膨胀系数向远离钨铼热电偶基体的方向逐渐增大,这样,相比简单的钨铼基体与只有一层的氧阻挡层的组合,它将原本热膨胀系数大的差异通过成分梯度或浓度梯度以渐变的形式分散到了层与层之间,使得热膨胀系数由内而外缓缓增大,有效减小了钨铼热电偶高温抗氧化涂层的热应力,同时增大了钨铼热电偶高温抗氧化涂层的附着力。
(2)本发明氧阻挡材料为多层结构,其氧阻挡材料中各层材料不仅热膨胀系数向远离钨铼热电偶基体的方向呈递增状态,保证良好的应力分散,而且其各层材料的耐氧烧蚀能力向远离钨铼热电偶基体的方向也逐渐增大,这样在确保应力分散、抗氧化涂层高温下稳定不脱落的同时,耐氧烧蚀能力即抗氧化能力也得到保证,进一步体现本发明的钨铼热电偶抗氧化涂层中氧阻挡材料的优越性。
(3)本发明提出的钨铼热电偶抗氧化涂层及氧阻挡材料直接附着于钨铼热电偶丝基体表面,总厚度为200微米以内,该钨铼热电偶抗氧化涂层在2000℃以上能够持续工作30min以上不脱落,抗氧化时间长且温度响应速度快。
(4)本发明钨铼热电偶抗氧化涂层结构中的多层结构的氧阻挡材料,材料选择至关重要,当采用不同材料实现具有浓度梯度或成分梯度的多层结构氧阻挡材料时,不仅满足了热膨胀系数递增,实现应力良好分散的问题,同时实验证实了在同等厚度下相比较同一种材料的氧阻挡材料,耐氧烧蚀能力即抗氧化能力大大增强,说明不同成分种类的氧阻挡材料或层与层之间的氧阻挡材料发挥了协同促进作用,增强了总体抗氧化涂层的抗氧化能力,为该涂层实现2000℃以上持续工作30分钟以上提供了有力保证。
(5)本发明通过选择特定的氧阻挡材料,巧妙设计氧阻挡材料的多层结构,并设置层与层之间的成分梯度或浓度梯度,通过独特的设计构思与材料种类的精心选择,结合特定的制备工艺和参数选择,最终获得了一种钨铼热电偶高温抗氧化涂层的氧阻挡材料,其能够在2000℃以上持续抗氧化30min以上,抗氧化性能以及热电偶响应速度均远远优于现有技术的热电偶抗氧化涂层。
附图说明
图1是本发明实施例1提供的钨铼热电偶抗氧化涂层结构中的氧阻挡材料的结构示意图;
图2是本发明实施例1提供的钨铼热电偶抗氧化涂层结构中的氧阻挡材料覆盖在钨铼热电偶表面的外观图;
图3是本发明实施例1提供的钨铼热电偶抗氧化涂层结构中的氧阻挡材料经1000℃退火后的SEM微观结构;
图4是本发明实施例1提供的钨铼热电偶抗氧化涂层结构中的氧阻挡材料烧蚀10min后钨铼热电偶表面形貌;
图5本发明实施例2提供的钨铼热电偶抗氧化涂层结构中的氧阻挡材料涂层经2300℃氧乙炔焰烧蚀10分钟后的SEM照片;
图6为本发明实施例3提供的钨铼热电偶抗氧化涂层结构中的氧阻挡材料涂层经2500℃氧乙炔焰烧蚀35分钟后的SEM照片;
图7为本发明实施例4提供的钨铼热电偶抗氧化涂层结构中的氧阻挡材料的结构示意图;
图8为本发明实施例4提供的钨铼热电偶抗氧化涂层结构中的氧阻挡材料涂层经1000℃退火处理后,用2300℃以上氧乙炔焰进行烧蚀,其热电势随烧蚀时间的变化图。
具体实施方式
为了使本发明的目的、技术方案及优点更加清楚明白,以下结合附图及实施例,对本发明进行进一步详细说明。应当理解,此处所描述的具体实施例仅仅用以解释本发明,并不用于限定本发明。此外,下面所描述的本发明各个实施方式中所涉及到的技术特征只要彼此之间未构成冲突就可以相互组合。
本发明提供了一种钨铼热电偶抗氧化涂层结构中的氧阻挡材料,该氧阻挡材料位于钨铼热电偶抗氧化涂层结构的最外部,其为不低于2层的多层结构,所述氧阻挡材料中各层材料的热膨胀系数向远离所述钨铼热电偶基体的方向逐渐增大。作为其中的一种方案,该氧阻挡材料即为所述钨铼热电偶的抗氧化涂层,其直接附着于钨铼热电偶基体表面。多层结构的氧阻挡材料存在成分梯度或浓度梯度,即所述氧阻挡材料的多层结构中每一层采用不同的材料种类以形成成分梯度;或者每一层材料种类相同且至少为两种材料的混合物,但是各层中材料的配比不同以形成浓度梯度。氧阻挡材料最外层的热膨胀系数与所述基体热膨胀系数之差的绝对值不大于7×10-6K-1。氧阻挡材料中各层材料的耐氧烧蚀能力向远离所述钨铼热电偶基体的方向逐渐增大。耐氧烧蚀能力大小可以通过在氧焰中燃烧测试其耐氧烧蚀即抗氧化能力。氧阻挡材料选用在2000℃以上能起到氧阻挡或耐氧烧蚀作用的难熔金属氧化物、硼化物或氮化物。氧阻挡材料选自氧化硅、氧化铪、硼化铪、氮化铪、氧化锆、硼化锆、氮化锆和氧化钇中的一种或多种。氧阻挡材料总厚度为50~200微米,优选的厚度范围为100~200微米,氧阻挡材料的层数可以设置为5~20层,优选为10~20层。氧阻挡材料的厚度很重要,不能太厚否则热电偶温度响应速度受影响;当然也不能太薄,否则抗氧化涂层容易脱落,抗氧化性能不能得到保证,所以如何在温度响应速度与耐氧烧蚀能力之间取得平衡是关键。
本发明钨铼热电偶抗氧化涂层结构中多层结构的氧阻挡材料,材料选择至关重要,当采用不同材料实现具有浓度梯度或成分梯度的多层结构氧阻挡材料时,不仅满足了热膨胀系数递增,实现应力良好分散的问题,同时也取得了在同等厚度下相比较同一种材料的氧阻挡材料,耐氧烧蚀能力即抗氧化能力大大增强,说明不同成分种类的氧阻挡材料或层与层之间的氧阻挡材料发挥了协同促进作用,增强了总体抗氧化涂层的抗氧化能力,为该涂层实现2000℃以上持续工作30分钟以上提供了有力保证。
上述多层结构的氧阻挡材料用作钨铼热电偶抗氧化涂层结构中的氧阻挡材料,可直接设置于于钨铼热电偶基体表面作为该钨铼热电偶材料的抗氧化涂层,也可以在基体与该样阻挡材料之间设置过渡层。
上述钨铼热电偶抗氧化涂层结构的氧阻挡材料的制备方法,包括如下步骤:
(1)选择热膨胀系数与钨铼热电偶基体热膨胀系数之差的绝对值不大于6×10-6K-1的材料或材料的混合物作为氧阻挡材料,通过化学气相沉积法、热喷涂法或溶胶凝胶法在钨铼热电偶基体表面进行第一层氧阻挡材料的制备;
(2)依次更换每一层材料种类,或材料种类不更换,逐渐调配每一层中不同材料的浓度配比,按照步骤(1)相同的方法向远离钨铼热电偶基体的方向逐层沉积,使得制备得到的多层结构的氧阻挡材料中各层材料热膨胀系数向远离所述钨铼热电偶基体的方向逐渐增大,所述氧阻挡材料中各层材料的耐氧烧蚀能力向远离所述钨铼热电偶基体的方向也逐渐增大;逐层沉积至氧阻挡材料总厚度为50~200μm。
本发明钨铼热电偶抗氧化涂层结构中的氧阻挡材料可通过等离子体增强化学气相沉积法在基体或基体表面的过渡层外层沉积多层结构的氧阻挡材料,或用等离子喷涂法在基体或基体表面的过渡层外层喷涂多层结构的氧阻挡材料,也可采用溶胶凝胶法在基体或基体表面的过渡层外层凝结多层结构的氧阻挡材料,优选采用溶胶凝胶法制备氧阻挡材料。
以下为实施例:
实施例1
一种钨铼热电偶高温抗氧化涂层结构中的氧阻挡材料,该氧阻挡材料直接设置于钨铼热电偶基体即直径约为0.5mm的钨铼热电偶丝表面,即该氧阻挡材料即为该钨铼热电偶的抗氧化涂层,如图1所示,该抗氧化涂层一共有五层,第一层为ZrB2材料,热膨胀系数为6.5×10-6K-1,厚度为10μm;第二层为ZrB2-5%SiC材料,厚度为10μm;第三层为ZrB2-10%SiC,厚度为10μm;第四层为ZrB2-15%SiC,厚度为10μm;第五层为ZrB2-20%SiC,热膨胀系数为9×10-6K-1,厚度为10μm。该多层结构的氧阻挡材料总厚度为50微米,其热膨胀系数以及耐氧烧蚀能力向远离钨铼热电偶基体的方向均逐渐增大。
该钨铼热电偶抗氧化涂层结构中氧阻挡材料的制备方法为:
先用八水合氧氯化锆(10~20wt%)、聚乙二醇4000(10~20wt%)和去离子水(60~80wt%)制备锆溶胶,然后用氨水调节溶胶PH值为2~3,陈化数日稳定后取一定量于烧杯中掺入二氧化锆粉(溶胶质量的10~40%),均匀搅拌制成悬浮液,再采用提拉机将钨铼热电偶浸入-拉出-干燥制得第一层;取等量溶胶,将二氧化锆粉和碳化硅粉(总质量占溶胶质量的10~40%)按质量比19:1加入到溶胶中去,重复浸入-拉出-干燥步骤制得第二层;另取等量溶胶,将二氧化锆粉和碳化硅粉(总质量占溶胶质量的10~40%)按质量比18:2加入到溶胶中去,重复浸入-拉出-干燥步骤制得第三层;另取等量溶胶,将二氧化锆粉和碳化硅粉(总质量占溶胶质量的10~40%)按质量比17:3加入到溶胶中去,重复浸入-拉出-干燥步骤制得第四层;另取等量溶胶,将二氧化锆粉和碳化硅粉(总质量占溶胶质量的10~40%)按质量比16:4加入到溶胶中去,重复浸入-拉出-干燥步骤制得第五层;制得五层具有成分梯度的钨铼热电偶抗氧化涂层。图2是氧阻挡材料覆盖在钨铼热电偶表面的外观图。
经1000℃退火处理后,用2000℃左右氧乙炔焰进行烧蚀,图3是氧阻挡层材料经1000℃退火后的SEM微观结构,可以看到涂层较为致密,孔隙率较少。图4是烧蚀10min后钨铼热电偶表面形貌,可以看出涂层表面产生的熔融态物质将裂纹填充,晶粒明显变大,说明短时间内涂层具有较好的保护作用,基底未被明显氧化。
实施例2
一种钨铼热电偶高温抗氧化涂层结构中的氧阻挡材料,该氧阻挡材料直接设置于钨铼热电偶基体即直径约为0.5mm的钨铼热电偶丝表面,即该氧阻挡材料即为该钨铼热电偶的抗氧化涂层,该抗氧化涂层一共有六层,第一层为SiC材料,热膨胀系数为4.5×10-6K-1,厚度为20μm;第二层为SiC-20%HfC材料,厚度为20μm;第三层为SiC-40%HfC,厚度为20μm;第四层为SiC-60%HfC,厚度为20μm;第五层为SiC-80%HfC,厚度为20μm;第六层为HfC,热膨胀系数为6.7×10-6K-1,厚度为20μm。该多层结构的氧阻挡材料总厚度为120微米,其热膨胀系数以及耐氧烧蚀能力向远离钨铼热电偶基体的方向均逐渐增大。
该钨铼热电偶抗氧化涂层结构中氧阻挡材料的制备方法为:
以氢气(流速约为750sccm)、甲基三氯硅烷(流速约为200sccm)和四氯化铪(流速约为100sccm)作为反应气相,以氩气为载体(流速约为350sccm),按各层涂层成分调节反应气相中各气源的占比,在850mTorr左右低压、900℃左右高温下通过低压化学气相沉积的方法可以制得成分占比渐变的多层x%SiC-y%HfC薄层,沉积速度约为3μm/h。
制得的多层涂层经1000℃退火处理后,用2300℃以上氧乙炔焰进行烧蚀,图5为涂层经2300℃氧乙炔焰烧蚀10分钟后的SEM照片。由图5可见,涂层表面经长时间高温火焰冲刷而出现开裂,但未见明显贯通裂纹。
实施例3
一种钨铼热电偶高温抗氧化涂层结构中的氧阻挡材料,该氧阻挡材料直接设置于钨铼热电偶基体即直径约为0.5mm的钨铼热电偶丝表面,即该氧阻挡材料即为该钨铼热电偶的抗氧化涂层,该抗氧化涂层一共有十一层,第一层为HfO2材料,热膨胀系数为4.3×10- 6K-1,厚度为20μm;第二层为HfO2-10%YSZ(钇稳定氧化锆,摩尔比Y:Zr=6:100)材料,厚度为20μm;第三层为HfO2-20%YSZ,厚度为20μm;第四层为HfO2-30%YSZ,厚度为20μm;第五层为HfO2-40%YSZ,厚度为20μm;第六层为HfO2-50%YSZ,厚度为20μm;第七层为HfO2-60%YSZ,厚度为20μm;第八层为HfO2-70%YSZ,厚度为20μm;第九层为HfO2-80%YSZ,厚度为20μm;第十层为HfO2-90%YSZ,厚度为20μm;第十一层为YSZ,热膨胀系数为11.5×10-6K-1,厚度为20μm。该多层结构的氧阻挡材料总厚度为210微米,其热膨胀系数以及耐氧烧蚀能力向远离钨铼热电偶基体的方向均逐渐增大。
该钨铼热电偶抗氧化涂层结构中氧阻挡材料的制备方法为:
先用八水合氧氯化铪(10~20wt%)、聚乙二醇4000(10~20wt%)和去离子水(60~80wt%)制备铪溶胶,然后用氨水调节溶胶PH值为2~3,陈化数日稳定后取一定量于烧杯中掺入二氧化铪粉(溶胶质量的10~40%),均匀搅拌制成悬浮液,再采用提拉机将钨铼热电偶浸入-拉出-干燥制得第一层;取等量溶胶,将二氧化铪粉和氧化锆-6%摩尔氧化钇粉(总质量占溶胶质量的10~40%)按质量比9:1加入到溶胶中去,重复浸入-拉出-干燥步骤制得第二层;另取等量溶胶,将二氧化铪粉和氧化锆-6%摩尔氧化钇粉(总质量占溶胶质量的10~40%)按质量比8:2加入到溶胶中去,重复浸入-拉出-干燥步骤制得第三层;依次类推,制得十一层具有成分梯度的钨铼热电偶抗氧化涂层。
制得的多层涂层经1000℃退火处理后,用2500℃以上氧乙炔焰进行烧蚀,图6为涂层经2500℃氧乙炔焰烧蚀35分钟后的SEM照片。由图6可见,涂层表面经长时间高温火焰冲刷而逐层剥离、开裂,但WRe热电偶基体形态基本保持完好。
实施例4
一种钨铼热电偶高温抗氧化涂层结构中的氧阻挡材料,该氧阻挡材料与钨铼热电偶基体即直径约为0.5mm的钨铼热电偶丝表面之间还加有一层10μm左右厚度的TaC过渡层,如图7所示,氧阻挡材料一共有七层,靠近钨铼热电偶基体为第一层,第一层为HfC-10%ZrC材料,热膨胀系数为6×10-6K-1,厚度为20μm;第二层为HfC-30%ZrC材料,厚度为20μm;第三层为HfC-50%ZrC,厚度为20μm;第四层为ZrC,热膨胀系数为7.3×10-6K-1,厚度为20μm;第五层为ZrC-10%ZrO2,厚度为20μm;第六层为ZrC-30%ZrO2,厚度为20μm;第七层为ZrC-50%ZrO2,厚度为20μm。该多层结构的氧阻挡材料总厚度为140微米,其热膨胀系数以及耐氧烧蚀能力向远离钨铼热电偶基体的方向均逐渐增大。
该钨铼热电偶抗氧化涂层结构中氧阻挡材料的制备方法为:
先通过球磨对碳化铪、碳化锆以及氧化锆粉末分别进行细化处理,按照上述成分含量调整它们的质量比,然后通过等离子喷涂机控制喷涂距离150mm,喷涂功率30kW,送粉速率3kg/h,分别将具有不同成分占比的a%HfC-b%ZrC-c%ZrO2的包覆粉末喷涂在过渡层外层,依次制得七层具有成分梯度的钨铼热电偶氧阻挡材料。
制得的多层涂层经1000℃退火处理后,用2300℃以上氧乙炔焰进行烧蚀,图8是其热电势随烧蚀时间的变化,可见850s时仍有热电动势产生,说明钨铼热电偶未被破坏,仍能正常工作,抗氧化涂层的防护效果显著。
本领域的技术人员容易理解,以上所述仅为本发明的较佳实施例而已,并不用以限制本发明,凡在本发明的精神和原则之内所作的任何修改、等同替换和改进等,均应包含在本发明的保护范围之内。

Claims (10)

1.一种钨铼热电偶抗氧化涂层结构中的氧阻挡材料,其特征在于,其为不低于2层的多层结构,所述氧阻挡材料中各层材料的热膨胀系数向远离所述钨铼热电偶基体的方向逐渐增大。
2.如权利要求1所述的氧阻挡材料,其特征在于,所述多层结构的氧阻挡材料存在成分梯度或浓度梯度,即所述氧阻挡材料的多层结构中每一层采用不同的材料种类以形成成分梯度;或者每一层材料种类相同且至少为两种材料的混合物,但是各层中材料的配比不同以形成浓度梯度。
3.如权利要求1所述的氧阻挡材料,其特征在于,所述氧阻挡材料最外层的热膨胀系数与所述基体热膨胀系数之差的绝对值不大于7×10-6K-1
4.如权利要求1所述的氧阻挡材料,其特征在于,所述氧阻挡材料中各层材料的耐氧烧蚀能力向远离所述钨铼热电偶基体的方向逐渐增大。
5.如权利要求1所述的氧阻挡材料,其特征在于,所述氧阻挡材料选用在2000℃以上能起到氧阻挡或耐氧烧蚀作用的难熔金属氧化物、硼化物或氮化物。
6.如权利要求1所述的氧阻挡材料,其特征在于,所述氧阻挡材料选自氧化硅、氧化铪、硼化铪、氮化铪、氧化锆、硼化锆、氮化锆和氧化钇中的一种或多种。
7.如权利要求1所述的氧阻挡材料,其特征在于,所述氧阻挡材料总厚度为50~200微米。
8.如权利要求1所述的氧阻挡材料,其特征在于,所述氧阻挡材料的层数为5~20层。
9.一种如权利要求1~8任意一项所述的氧阻挡材料的应用,其特征在于,用作钨铼热电偶抗氧化涂层结构中的氧阻挡材料,该氧阻挡材料位于所述钨铼热电偶抗氧化涂层结构的最外部。
10.如权利要求9所述的应用,其特征在于,所述氧阻挡材料附着于所述钨铼热电偶基体表面;优选地,通过化学气相沉积法、热喷涂法或溶胶凝胶法在所述钨铼热电偶基体表面制备得到所述氧阻挡材料。
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