CN109608200B - 一种碳硅化铝结合SiC质耐火材料及其制备方法 - Google Patents

一种碳硅化铝结合SiC质耐火材料及其制备方法 Download PDF

Info

Publication number
CN109608200B
CN109608200B CN201811503341.5A CN201811503341A CN109608200B CN 109608200 B CN109608200 B CN 109608200B CN 201811503341 A CN201811503341 A CN 201811503341A CN 109608200 B CN109608200 B CN 109608200B
Authority
CN
China
Prior art keywords
sic
silicon carbide
refractory material
aluminum
preparation
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active
Application number
CN201811503341.5A
Other languages
English (en)
Other versions
CN109608200A (zh
Inventor
顾华志
陈定
黄奥
张美杰
倪红卫
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Wuhan University of Science and Engineering WUSE
Original Assignee
Wuhan University of Science and Engineering WUSE
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Wuhan University of Science and Engineering WUSE filed Critical Wuhan University of Science and Engineering WUSE
Priority to CN201811503341.5A priority Critical patent/CN109608200B/zh
Publication of CN109608200A publication Critical patent/CN109608200A/zh
Application granted granted Critical
Publication of CN109608200B publication Critical patent/CN109608200B/zh
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Classifications

    • CCHEMISTRY; METALLURGY
    • C04CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04BLIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B35/00Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/515Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics
    • C04B35/56Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on carbides or oxycarbides
    • C04B35/565Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on carbides or oxycarbides based on silicon carbide
    • CCHEMISTRY; METALLURGY
    • C04CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04BLIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B35/00Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/515Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics
    • C04B35/56Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on carbides or oxycarbides
    • CCHEMISTRY; METALLURGY
    • C04CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04BLIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B35/00Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/66Monolithic refractories or refractory mortars, including those whether or not containing clay
    • CCHEMISTRY; METALLURGY
    • C04CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04BLIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2235/00Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/02Composition of constituents of the starting material or of secondary phases of the final product
    • C04B2235/30Constituents and secondary phases not being of a fibrous nature
    • C04B2235/40Metallic constituents or additives not added as binding phase
    • C04B2235/402Aluminium
    • CCHEMISTRY; METALLURGY
    • C04CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04BLIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2235/00Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/70Aspects relating to sintered or melt-casted ceramic products
    • C04B2235/96Properties of ceramic products, e.g. mechanical properties such as strength, toughness, wear resistance
    • CCHEMISTRY; METALLURGY
    • C04CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04BLIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2235/00Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/70Aspects relating to sintered or melt-casted ceramic products
    • C04B2235/96Properties of ceramic products, e.g. mechanical properties such as strength, toughness, wear resistance
    • C04B2235/9607Thermal properties, e.g. thermal expansion coefficient

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Ceramic Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Structural Engineering (AREA)
  • Organic Chemistry (AREA)
  • Compositions Of Oxide Ceramics (AREA)
  • Ceramic Products (AREA)

Abstract

本发明涉及一种碳硅化铝结合SiC质耐火材料及其制备方法,包括如下步骤:S1、将85~95wt%的碳化硅、0.1~10wt%的单质铝和2~8wt%的热固性酚醛树脂放入混碾机中混合均匀,压制成型制得碳化硅砖;S2、将步骤S1中所述碳化硅砖在一定条件下进行烘烤,再经过感应炉烧结得到原位生成Al4SiC4结合SiC质耐火材料。本发明制备的原位生成Al4SiC4结合SiC质耐火材料具有烧结温度低、烧结时间短、力学性能优异、抗氧化性强的特点。

Description

一种碳硅化铝结合SiC质耐火材料及其制备方法
技术领域
本发明涉及一种耐火材料及其制备方法,具体涉及一种碳硅化铝结合SiC质耐火材料及其制备方法,属于耐火材料技术领域。
背景技术
碳化硅质耐火材料具有优异的高温力学性能与抗渣性能,其作为高温炉衬被广泛应用于炼铁、有色冶金、垃圾焚烧、脱硫等行业。碳化硅制品按照结合方式主要有:氧化物结合、氮化硅结合及自结合等。氧化物结合碳化硅由于氧化物结合相与基体SiC膨胀系数不一致,导致热震稳定性较差;氮化硅结合及自结合碳化硅材料又存在高温下的氧化问题。
Al4SiC4具有层片状结构,其熔点高、抗氧化性强、高温力学性能优异,与SiC基体具有良好的兼容性,在SiC-C系耐火材料中引入Al4SiC4能够提高力学性能与抗氧化性能。Zhang在MgO-C和Al2O3-C材料中加入Al4SiC4显著提高了材料的抗氧化性能[Zhang S,Yamaguchi A.Effect of Al4SiC4 addition to carbon-containingrefractories.J.Ceram.Soc.Jpn.,1995,103(1195):235-239]。相比于在原料中直接添加Al4SiC4,原位合成Al4SiC4能够使其均匀分布在耐火材料中,与SiC基体具有很高的界面结合强度,制备工艺简单,材料力学性能优异。Chen以Al、Si和炭黑为原料,在Ar气氛下经过1800℃×3h处理,得到高纯度的Al4SiC4[Chen J H,Zhang Z H,Mi W J,et al.Fabricationand oxidation behavior of Al4SiC4 powders.J.Am.Ceram.S.,2017,100(7):3145-3154]。Yu以炭黑还原铝矾土和硅石,在流动Ar气氛下经过1800℃×3h处理,得到六方片状Al4SiC4[Yu C,Yuan W,Deng C,et al.Synthesis of hexagonal plate-like Al4SiC4fromcalcined bauxite,silica and carbon black.Powder technol.,2013,247:76-80]。钱志明在1300℃~1700℃下保温5~12h制备了Al4SiC4结合Al2O3-SiC复合材料[CN 108218408A],具有优异的力学性能;然而上述合成Al4SiC4的方法反应温度高、保温时间长。感应加热具有升温速率快、合成温度低、工艺简单和节能环保的特点,有利于Al4SiC4的低温合成。
发明内容
为解决现有技术不足,本发明提供了一种碳硅化铝结合SiC质耐火材料的制备方法,用该方法制备的原位生成Al4SiC4结合SiC质耐火材料的烧结温度低、烧结时间短、力学性能优异、抗氧化性强。
本发明的目的是通过下述技术方案实现的:
一种碳硅化铝(Al4SiC4)结合SiC质耐火材料的制备方法,包括如下步骤:
S1、将85~95wt%的碳化硅、0.1~10wt%的单质铝和2~8wt%的热固性酚醛树脂放入混碾机中混合均匀,压制成型制得碳化硅砖;
S2、将步骤S1中所述碳化硅砖先经过烘烤,再经过感应炉烧结,所述感应炉烧结条件为:以10~20℃/min的速率升温到1200~1700℃,保温0.5~4h,然后自然降温,并通入氩气保护,得到原位生成Al4SiC4结合SiC质耐火材料。
基于上述技术方案,形成Al4SiC4需要经过烧结,然而一般需要的烧结方式需要在1700℃以上长时间保温才能够形成Al4SiC4,感应烧结可在较低温度下短时间内形成Al4SiC4
进一步的,所述碳化硅中SiC含量≥98wt%。
进一步的,所述单质铝中Al含量≥99wt%,所述单质铝的粒径≤38μm。
进一步的,所述热固性酚醛树脂残碳量≥40wt%。
进一步的,所述烘烤条件为:在120~250℃下烘烤24~30h。
本发明还提供了一种用所述碳硅化铝结合SiC质耐火材料的制备方法制备得到的碳硅化铝结合SiC质耐火材料。
本发明的有益效果在于:
本发明以SiC为主要原料,酚醛树脂为结合剂制备碳化硅砖,采用感应烧结的方式对SiC砖进行热处理,感应线圈在交变电流的作用下产生交变磁场,在交变磁场作用下,洛伦兹力使得碳化硅砖中熔化的Al液产生电磁搅拌作用而不断运动,促进传质与传热,当Al液中吸收一定的残碳后能够迅速反应生成Al4C3,且Al液运动会裹挟细小的SiC基质,促进Al4C3与之反应生成Al4SiC4,最终形成原位Al4SiC4结合SiC质耐火材料。
本发明制备的原位生成Al4SiC4结合SiC质耐火材料,经检测:显气孔率为8%~16%,耐压强度为81~100MPa;热震稳定性能好;经过1500℃空气气氛氧化10h,增重率为0.06~0.2%。
因此,本发明制备的原位生成Al4SiC4结合SiC质耐火材料具有烧结温度低、烧结时间短、力学性能优异、抗氧化性强的特点。
具体实施方式
以下结合具体实施例对本发明的原理和特征进行描述,所举实例只用于解释本发明,并非用于限定本发明的范围。
实施例1
以85wt%的碳化硅、0.1wt%的单质铝和2wt%的热固性酚醛树脂为原料,在混碾机中混合均匀,然后压制成型制得碳化硅砖;将上述碳化硅砖在120℃条件下烘烤24小时,再经过感应炉烧结,以10℃/min的速率升温至在1200℃下保温0.5h,即得原位生成Al4SiC4结合SiC质耐火材料。
本实施例制备的原位生成Al4SiC4结合SiC质耐火材料,经检测:显气孔率为8%~10%,耐压强度为95~100MPa;热震稳定性能好;经过1500℃空气气氛氧化10h,增重率为0.06~0.1%。
实施例2
以95wt%的碳化硅、10wt%的单质铝和8wt%的热固性酚醛树脂为原料,在混碾机中混合均匀,然后压制成型制得碳化硅砖;将上述碳化硅砖在250℃条件下烘烤30小时,再经过感应炉烧结,以20℃/min的速率升温至在1700℃下保温4h,即得原位生成Al4SiC4结合SiC质耐火材料。
本实施例制备的原位生成Al4SiC4结合SiC质耐火材料,经检测:显气孔率为9%~12%,耐压强度为92~97MPa;热震稳定性能好;经过1500℃空气气氛氧化10h,增重率为0.09~0.13%。
实施例3
以87wt%的碳化硅、5.5wt%的单质铝和5wt%的热固性酚醛树脂为原料,在混碾机中混合均匀,然后压制成型制得碳化硅砖;将上述碳化硅砖在180℃条件下烘烤26小时,再经过感应炉烧结,以15℃/min的速率升温至在1500℃下保温2.5h,即得原位生成Al4SiC4结合SiC质耐火材料。
本实施例制备的原位生成Al4SiC4结合SiC质耐火材料,经检测:显气孔率为11%~13%,耐压强度为86~93MPa;热震稳定性能好;经过1500℃空气气氛氧化10h,增重率为0.12~0.15%。
实施例4
以86wt%的碳化硅、7wt%的单质铝和3wt%的热固性酚醛树脂为原料,在混碾机中混合均匀,然后压制成型制得碳化硅砖;将上述碳化硅砖在175℃条件下烘烤27小时,再经过感应炉烧结,以17℃/min的速率升温至在1350℃下保温2.5h,即得原位生成Al4SiC4结合SiC质耐火材料。
本实施例制备的原位生成Al4SiC4结合SiC质耐火材料,经检测:显气孔率为12%~14%,耐压强度为84~91MPa;热震稳定性能好;经过1500℃空气气氛氧化10h,增重率为0.14~0.17%。
实施例5
以87.5wt%的碳化硅、0.8wt%的单质铝和6wt%的热固性酚醛树脂为原料,在混碾机中混合均匀,然后压制成型制得碳化硅砖;将上述碳化硅砖在200℃条件下烘烤25小时,再经过感应炉烧结,以16℃/min的速率升温至在1450℃下保温3h,即得原位生成Al4SiC4结合SiC质耐火材料。
本实施例制备的原位生成Al4SiC4结合SiC质耐火材料,经检测:显气孔率为13%~16%,耐压强度为81~85MPa;热震稳定性能好;经过1500℃空气气氛氧化10h,增重率为0.16~0.2%。
对比例
一种Al4SiC4/SiC复合耐火材料及其制备方法(CN101423404A)本对比例所述制备方法是:
先将50~65wt%的粘土和35~50wt%的工业炭粉混合,外加上述混合物3~10wt%的结合剂,搅拌5~25分钟,压制成型,在60~110℃条件下干燥12~36小时或在室内自然干燥24~48小时;然后在氩气气氛下和在1600~1800℃下2~6小时条件下烧结,自然冷却后制得Al4SiC4/SiC复合材料。本发明制备时间较长,耗能较高。
以上所述仅为本发明的较佳实施例,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、改进等,均应包含在本发明的保护范围之内。

Claims (3)

1.一种碳硅化铝结合SiC质耐火材料的制备方法,其特征在于,包括如下步骤:
S1、将85~95wt%的碳化硅、0.1~10wt%的单质铝和2~8wt%的热固性酚醛树脂放入混碾机中混合均匀,压制成型制得碳化硅砖;其中,所述碳化硅中SiC含量≥98wt%;所述单质铝中Al含量≥99wt%,所述单质铝的粒径≤38μm;所述热固性酚醛树脂残碳量≥40wt%;
S2、将步骤S1中所述碳化硅砖先经过烘烤,再经过感应炉烧结,所述感应炉烧结条件为:以10~20℃/min的速率升温到1200~1700℃,保温0.5~4h,然后自然降温,并通入氩气保护,得到原位生成Al4SiC4结合SiC质耐火材料。
2.根据权利要求1所述碳硅化铝结合SiC质耐火材料的制备方法,其特征在于,所述烘烤条件为:在120~250℃下烘烤24~30h。
3.一种如权利要求1至2任一所述碳硅化铝结合SiC质耐火材料的制备方法制备得到的碳硅化铝结合SiC质耐火材料。
CN201811503341.5A 2018-12-10 2018-12-10 一种碳硅化铝结合SiC质耐火材料及其制备方法 Active CN109608200B (zh)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN201811503341.5A CN109608200B (zh) 2018-12-10 2018-12-10 一种碳硅化铝结合SiC质耐火材料及其制备方法

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN201811503341.5A CN109608200B (zh) 2018-12-10 2018-12-10 一种碳硅化铝结合SiC质耐火材料及其制备方法

Publications (2)

Publication Number Publication Date
CN109608200A CN109608200A (zh) 2019-04-12
CN109608200B true CN109608200B (zh) 2021-06-29

Family

ID=66007628

Family Applications (1)

Application Number Title Priority Date Filing Date
CN201811503341.5A Active CN109608200B (zh) 2018-12-10 2018-12-10 一种碳硅化铝结合SiC质耐火材料及其制备方法

Country Status (1)

Country Link
CN (1) CN109608200B (zh)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110627507B (zh) * 2019-09-18 2022-02-25 广东工业大学 一种低温碳化硅陶瓷及其制备方法和应用
CN114349520A (zh) * 2021-12-02 2022-04-15 北京科技大学 一种高炉本体用Al4SiC4-SiC复合耐火材料及其制备方法
CN115894037B (zh) * 2022-11-21 2024-02-06 洛阳亿特立新材料科技有限公司 一种Al4SiC4结合碳化硅多孔陶瓷及其制备方法

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101423403A (zh) * 2008-11-20 2009-05-06 武汉科技大学 一种碳硅化铝和碳化硅复合材料及其制备方法
CN101423404A (zh) * 2008-11-20 2009-05-06 武汉科技大学 一种Al4SiC4/SiC复合耐火材料及其制备方法
CN101824576A (zh) * 2009-03-04 2010-09-08 中国科学院金属研究所 一种锆铝硅碳-碳化硅复合材料及其制备方法
RO126848A0 (ro) * 2011-06-21 2011-11-30 Ştefan Mircea Aditivi antioxidanţi pentru fabricarea produselor refractare mgo-c şi alo-c
CN102730690A (zh) * 2012-06-16 2012-10-17 山东科技大学 一种Al4SiC4材料的合成方法
CN105801143A (zh) * 2016-04-01 2016-07-27 瑞泰科技股份有限公司 一种高抗侵蚀性碳化硅砖及其制备方法
CN108218408A (zh) * 2017-12-13 2018-06-29 江苏诺明高温材料股份有限公司 一种Al4SiC4结合Al2O3-SiC复合材料的制备方法

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101423403A (zh) * 2008-11-20 2009-05-06 武汉科技大学 一种碳硅化铝和碳化硅复合材料及其制备方法
CN101423404A (zh) * 2008-11-20 2009-05-06 武汉科技大学 一种Al4SiC4/SiC复合耐火材料及其制备方法
CN101824576A (zh) * 2009-03-04 2010-09-08 中国科学院金属研究所 一种锆铝硅碳-碳化硅复合材料及其制备方法
RO126848A0 (ro) * 2011-06-21 2011-11-30 Ştefan Mircea Aditivi antioxidanţi pentru fabricarea produselor refractare mgo-c şi alo-c
CN102730690A (zh) * 2012-06-16 2012-10-17 山东科技大学 一种Al4SiC4材料的合成方法
CN105801143A (zh) * 2016-04-01 2016-07-27 瑞泰科技股份有限公司 一种高抗侵蚀性碳化硅砖及其制备方法
CN108218408A (zh) * 2017-12-13 2018-06-29 江苏诺明高温材料股份有限公司 一种Al4SiC4结合Al2O3-SiC复合材料的制备方法

Also Published As

Publication number Publication date
CN109608200A (zh) 2019-04-12

Similar Documents

Publication Publication Date Title
CN107879753B (zh) 一种碳化硅-镁铝尖晶石复合耐火材料
CN109608200B (zh) 一种碳硅化铝结合SiC质耐火材料及其制备方法
EP1955987B1 (en) Refractory brick
CN102730690B (zh) 一种Al4SiC4材料的合成方法
CN111704466B (zh) 一种碳化硅-镁铝尖晶石-铝复合耐火材料
JP2014198662A (ja) 緻密質複合材料、その製法及び半導体製造装置用部材
Behera et al. Nano carbon containing low carbon magnesia carbon refractory: an overview
CN102093065B (zh) 一种以复合镁砂为主要原料的镁碳砖及制备方法
CN111662090A (zh) 一种镁铝尖晶石-碳化硅-铝复合耐火材料
JP5622325B2 (ja) アルミニウムオキシカーバイド組成物及びその製造方法、並びに耐火物
JP5448190B2 (ja) 溶融金属保持炉の内張り用アルミナカーボン系不焼成れんが及び製造方法、並びにそれを用いた窯炉設備及び施工方法
CN109704797A (zh) 一种短切碳纤维增强Cf/SiC复合材料的制备方法
CN110483023B (zh) 一种微孔化刚玉砖及其制备方法
CN111646812A (zh) 一种碳化硅-六铝酸钙-铝复合耐火材料
CN107043265B (zh) 一种冶金、有色熔炼炉用不烧镁铬砖及其制备方法
CN106866126A (zh) 一种刚玉‑尖晶石质耐火砖及其制备方法
JP2012031026A (ja) アルミナ−マグネシア質耐火れんが及びその製造方法
CN115417662B (zh) 一种氢冶金用微孔刚玉砖及其制备方法
CN113636852B (zh) 球壳-海绵结构六铝酸钙-镁铝尖晶石复相材料的制备方法
CN104193363B (zh) 一种提高MgO-C砖强度的方法
WO2019049992A1 (ja) 不定形耐火物
CN1654416A (zh) 一种方镁石—碳化硅复合材料及其制备方法
KR102650353B1 (ko) 내화 배치, 상기 배치로부터 부정형 내화 세라믹 제품을 제조하는 방법 및 상기 방법에 의해 수득한 부정형 내화 세라믹 제품
CN107324790A (zh) 镁橄榄石-碳化硅复合陶瓷材料及其合成方法
CN114315391A (zh) 一种可膨胀镁碳火泥及其制备方法和应用

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant