废SCR钛基脱硝催化剂铝热还原重熔制备含铬钛铝基合金的试验研究
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摘要
首次利用废选择性催化还原(SCR)脱硝催化剂为原料,采用铝热还原—重熔法进行了Ti-Al基合金制备的试验研究,并通过添加不同含量的Cr元素,研究Cr对合金微观组织、物相组成及性能的影响。通过X射线衍射(XRD)和能谱(EDS)分析,发现未添加Cr元素的合金中所观察到的相主要由Ti_(0.8)V_(0.2)Al_3、TiAl_2、Ti_3Al、TiAl等钛铝金属间化合物,Ti_5Si_3、TiSi_2等钛硅化合物,CaAl_4O_7、Ca_2AlSiO_(5.5)等氧化物组成。添加Cr元素可降低高铝型钛铝化合物的形成,减少钙铝氧化物含量,形成含铬元素的Ti_(0.25)Cr_(0.08)Al_(0.67)相,增加Ti_3Al与TiAl类物相的生成。通过Pandat热化学软件的物相衍变计算得出,Cr的添加可大幅度降低Al_3(Ti,V)的相比率,降低一定量的(Ti,Cr)_5Si_3相比率,同时增加TiAl相的形成。硬度测试结果表明,随Cr含量的增加,合金硬度整体呈上升趋势。这可能是由于等轴晶TiAl类物相的均匀分布和(Ti,W)_5Si_3相的减少所导致的。
Ti-Al based alloys were prepared for the first time by aluminothermic reduction-remelting method using scrap selective catalytic reduction(SCR) catalyst as raw material.The effects of Cr on the microstructure,phase compositions and properties of the alloys were also studied by adding different contents of Cr.X-ray diffraction(XRD) and energy dispersive spectroscopy(EDS) analysis show that the phases observed in the alloys without adding Cr element are mainly composed of Ti_(0.8)V_(0.2)Al_3,TiAl_2,Ti_3Al,TiAl,Ti_5Si_3,TiSi_2,CaAl_4O_7,Ca_2AlSiO_(5.5) and so on.Adding Cr element can reduce the formation of Al-rich titanium aluminide compounds,and reduce the content of Ca-Al oxides.It can also form Ti_(0.25)Cr_(0.08)Al_(0.67) phase,and increases the formation of Ti_3Al and TiAl phases.The phase evolution calculation by Pandat thermochemical software shows that the addition of Cr can significantly reduce the phase ratio of Al_3(Ti,V) and decrease a certain amount of(Ti,Cr)_5Si_3,and can increase the formation of TiAl phase.The hardness test results show that the hardness of the alloy increases with the increase of Cr content.This may be due to the uniform distribution of equiaxed TiAl-like phases and the decrease of(Ti,W)_5Si_3 phase.
Ti-Al based alloys were prepared for the first time by aluminothermic reduction-remelting method using scrap selective catalytic reduction(SCR) catalyst as raw material.The effects of Cr on the microstructure,phase compositions and properties of the alloys were also studied by adding different contents of Cr.X-ray diffraction(XRD) and energy dispersive spectroscopy(EDS) analysis show that the phases observed in the alloys without adding Cr element are mainly composed of Ti_(0.8)V_(0.2)Al_3,TiAl_2,Ti_3Al,TiAl,Ti_5Si_3,TiSi_2,CaAl_4O_7,Ca_2AlSiO_(5.5) and so on.Adding Cr element can reduce the formation of Al-rich titanium aluminide compounds,and reduce the content of Ca-Al oxides.It can also form Ti_(0.25)Cr_(0.08)Al_(0.67) phase,and increases the formation of Ti_3Al and TiAl phases.The phase evolution calculation by Pandat thermochemical software shows that the addition of Cr can significantly reduce the phase ratio of Al_3(Ti,V) and decrease a certain amount of(Ti,Cr)_5Si_3,and can increase the formation of TiAl phase.The hardness test results show that the hardness of the alloy increases with the increase of Cr content.This may be due to the uniform distribution of equiaxed TiAl-like phases and the decrease of(Ti,W)_5Si_3 phase.
引文
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[16] Chen S L,Daniel S,Zhang F,et al.The Pandat software package and its application[J].Calphad,2002,26(2):175-188.
[2] Chen C ,Lu Q,Lin Z,et al.Research progress of element recovery of waste De-NOx SCR catalyst from coal-fired power plants[J].Chemical Industry and Engineering progress,2016,35(10):3306-3312.
[3] Casanova M,Rocchini E ,Trovarelli A,et al.High-temperature stability of V2O5/TiO2-WO3- SiO2 SCR catalysts modified with rare-earths[J].Journal of Alloys and Compounds,2006,408-412:1108-1112.
[4] Imam M A.The 13th world conference on titanium (Ti-2015)[J].JOM,2016,68(9):2492-2501.
[5] Clemens H,Kestler H.Processing and applications of intermetallic γ-TiAl based alloys[J].Advanced Engineering Material.2000,2(9):551-570.
[6] Kunal K,Ramachandran R,Norman M W.Advances in gamma titanium aluminides and their manufacturing techniques[J].Progress in Aerospace Sciences,2012,55:1-16.
[7] Zhou W.Titanium handbook[M].Beijing:Chemical Industry Press,2012.
[8] Hall Fred W.Aluminthermic processes[M].Weinheim:Wiley-VCH Verlag GmbH & Co.KGaA,2000.
[9] Taniguchi S,Shibata T.Intennetallic of oxygen partial pressure on the oxidation behavior of TiAl at 1 300 K[J].Materials Science and Engineering,1997,232(1):47-54.
[10] Zhang Liang.Effect of Cr on high temperature oxidation resistance of TiAl alloy[D].Beijing:Beijing University of Aeronautics and Astronautics,2006.(张亮.Cr对TiAl合金高温抗氧化性能的影响[D].北京:北京航空航天大学,2006.)
[11] Wu X,Huang A,Loretto M H,et al.Oxidation-induced embrittlement of TiAl alloys[J].Intermetallies,2009,17(7):540.
[12] Kunal Kothari,Ramachandran Radhakrishnan,Norman M Wereley.Advances in gamma titanium aluminides and their manufacturing techniques[J].Progress in Aerospace Sciences,2012,55:1-16.
[13] Ma L,Piao R,Yang S,et al.Preparation of multi-components Ti-Al based alloy by aluminothermic reduction of acid soluble titanium bearing slag[J].Rare Metal Materials and Engineering,2018,47(5):1411-1421.
[14] Piao Rongxun,Ma Lan,Yang Shaoli ,et al.Material proportioning calculations for aluminothermic reduction of Ti-containing slag[J].Iron Steel Vanadium Titanium ,2018,39 (4):36-40.(朴荣勋,马兰,杨绍利,等.钛渣铝热还原的材料配比计算[J].钢铁钒钛,2018,39(4):36-40.)
[15] Ma Lan,Piao Rongxun,Yang Shaoli,et al.Experimental study of vacuum electromagnetic levitation refining of TiAl intermetallic alloy[J].Iron Steel Vanadium Titanium,2017,38(3):45-51.(马兰,朴荣勋,杨绍利,等.真空电磁悬浮精炼钛铝基中间合金试验研究[J].钢铁钒钛,2017,38(3):45-51.)
[16] Chen S L,Daniel S,Zhang F,et al.The Pandat software package and its application[J].Calphad,2002,26(2):175-188.