镁基六铝酸镧喷涂粉末制备及其热处理工艺研究
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摘要
采用固相反应法合成热障涂层用镁基六铝酸镧(LaMgAl_(11)O_(19)),通过离心喷雾干燥造粒制备LaMgAl_(11)O_(19)粉末,并对粉末进行热处理研究,将未热处理和热处理后的粉末通过等离子喷涂制备LaMgAl_(11)O_(19)涂层并在1100℃高温氧化1 h。通过场发射扫描电子显微镜、霍尔流量计、X射线衍射等方法对LaMgAl_(11)O_(19)粉末的微观形貌、流动性、松装密度、物相和涂层形貌进行了分析。结果表明:离心喷雾干燥造粒工艺获得了粒径均匀、流动性好的LaMgAl_(11)O_(19)球形粉末,但粉末颗粒内部结构疏松不致密;热处理能明显改善LaMgAl_(11)O_(19)球形粉末的流动性和致密度,并能有效的避免涂层分解、改善涂层成分、提高涂层的性能。本试验中的最佳热处理温度为1450℃,与未热处理粉末相比,经过1450℃热处理后粉末的流动性为12.1 s·50 g-1,流动时间缩短了19.9%,松装密度提高了83.4%;制备的涂层孔隙率更低,结构更为致密,有效的降低了喷涂过程中涂层非晶相的形成。
Lanthanide magnesium hexaaluminate(LaMgAl_(11)O_(19)) synthesized successfully by solid-state reaction. LaMgAl_(11)O_(19) powder was prepared by centrifugal spray-drying, and the powder was heat treated. The La Mg Al11 O19 coating was prepared with unheated treatment powder and heat treatment powder by plasma spraying and oxidized at 1100 ℃ for 1 h. The flowability and apparent density, microstructure and phase of LaMgAl_(11)O_(19) powder were analyzed by Hall flowmeter, scanning electron microscope(SEM) and X-ray diffraction(XRD). The results show that centrifugal spray-drying obtained the uniform particle size and good fluidity La Mg Al11 O19 spherical powder, and the internal structure of the powder was loose and not dense. The heat treatment of La Mg Al11 O19 powder can improve the fluidity and relative density, and can avoid the decomposition of the coating effectively. The optimal temperature of heat treatment is 1450 ℃ in this test. Compared with the unheated treatment powder, the fluidity of the powder after heat treatment at 1450 ℃ is 12.1 s·50 g-1, the flow time is shortened by 19.9%, and the apparent density is increased by 83.4%. The coating prepared by the heat treatment powders have a lower porosity and a more compact structure, and reduces the formation of the amorphous phase during the spraying process effectively.
Lanthanide magnesium hexaaluminate(LaMgAl_(11)O_(19)) synthesized successfully by solid-state reaction. LaMgAl_(11)O_(19) powder was prepared by centrifugal spray-drying, and the powder was heat treated. The La Mg Al11 O19 coating was prepared with unheated treatment powder and heat treatment powder by plasma spraying and oxidized at 1100 ℃ for 1 h. The flowability and apparent density, microstructure and phase of LaMgAl_(11)O_(19) powder were analyzed by Hall flowmeter, scanning electron microscope(SEM) and X-ray diffraction(XRD). The results show that centrifugal spray-drying obtained the uniform particle size and good fluidity La Mg Al11 O19 spherical powder, and the internal structure of the powder was loose and not dense. The heat treatment of La Mg Al11 O19 powder can improve the fluidity and relative density, and can avoid the decomposition of the coating effectively. The optimal temperature of heat treatment is 1450 ℃ in this test. Compared with the unheated treatment powder, the fluidity of the powder after heat treatment at 1450 ℃ is 12.1 s·50 g-1, the flow time is shortened by 19.9%, and the apparent density is increased by 83.4%. The coating prepared by the heat treatment powders have a lower porosity and a more compact structure, and reduces the formation of the amorphous phase during the spraying process effectively.
引文
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[2]Padture N P,Gell M,Jordan E H.Thermal barrier coatings for gas-turbine engine applications.Science,2002,296(5566):280
[3]Lin F,Yu Y G,Jiang X L,et al.Microstructures and properties of nanostructured TBCs fabricated by plasma spraying.Chin J Nonferrous Met,2006,16(3):482(林锋,于月光,蒋显亮,等.等离子体喷涂纳米结构热障涂层微观组织及性能.中国有色金属学报,2006,16(3):482)
[4]Kokini K,DeJonge J,Rangaraj S,et al.Thermal shock of functionally graded thermal barrier coatings with similar thermal resistance.Surf Coat Technol,2002,154(2-3):223
[5]Kvernes I,Forseth S.Corrosion mechanisms of ceramic coatings in diesel engines.Mater Sci Eng,1987,88:61
[6]Zhou F F,Wang Y,Cui Z Y,et al.Thermal cycling behavior of nanostructured 8YSZ,SZ/8YSZ and8CSZ/8YSZ thermal barrier coatings fabricated by atmospheric plasma spraying.Ceram Int,2017,43(5):4102
[7]Wright P K.Influence of cyclic strain on life of a PVDTBC.Mater Sci Eng A,1998,245(2):191
[8]Bansal N P,Zhu D M.Thermal properties of oxides with magnetoplumbite structure for advanced thermal barrier coatings.Surf Coat Technol,2008,202(12):2698
[9]Huang L L,Meng H M,Chen L.Research status of hexaaluminate thermal barrier coatings with magnetoplumbite structure.J Mater Eng,2013(12):92(黄亮亮,孟惠民,陈龙.磁铅石结构六铝酸盐热障涂层的研究现状.材料工程,2013(12):92)
[10]Jiang B,Fang M H,Huang C H,et al.Preparation of Gd3+-doped La1-xGdxMgAl11O19(x=0-1)ceramics and its thermal properties.J Chin Ceram Soc,2010,38(7):1263(姜斌,房明浩,黄朝晖,等.Gd3+掺杂La1-xGdxMg Al11O19(x=0~1)陶瓷的制备及热学性能.硅酸盐学报,2010,38(7):1263)
[11]Zhu R X,Liu Z G,Ouyang J H,et al.Preparation and characterization of LnMgAl11O19(Ln=La,Nd,Gd)ceramic powders.Ceram Int,2013,39(8):8841
[12]Li P Z,Xie M,Zhao M,et al.Preparation and characterization of LaMgAl11O19 used as thermal barrier coat materials.Chin Rare Earths,2010,31(1):26(李培忠,谢敏,赵鸣,等.镁基六铝酸镧热障涂层材料的制备及表征.稀土,2010,31(1):26)
[13]Liu H F,Li S L,Li Q L,et al.Preparation and phase stability of La2O3,Y2O3 co-doped ZrO2 ceramic powder application for thermal barrier coating.J Inorg Mater,2009,24(6):1226(刘怀菲,李松林,李其连,等.热障涂层用La2O3、Y2O3共掺杂ZrO2陶瓷粉末的制备及其相稳定性.无机材料学报,2009,24(6):1226)
[14]Zhou H M,Yi D Q,Xiao L R.Preparation of Ce O2-La2O3-Zr O2 ceramic powder by chemical precipitation method.Chin J Nonferrous Met,2007,17(2):265(周宏明,易丹青,肖来荣.化学沉淀法制备Ce O2-La2O3-Zr O2陶瓷粉末.中国有色金属学报,2007,17(2):265)
[15]Wu H Y,Zhang G J,Wang W C.Effects of sintering temperature on microstructure and properties of reaction bonded silicon carbide.Powder Metall Technol,2017,35(5):342(巫红燕,张国军,王伟春.烧结温度对反应烧结碳化硅组织与性能的影响.粉末冶金技术,2017,35(5):342)