等離子噴涂氧化鎢涂層的制備及二氧化氮氣敏性能研究
發(fā)布時間：2018-08-31 10:14
【摘要】：二氧化氮(NO2)是一種典型大氣污染物,可導致光化學煙霧與酸雨等環(huán)境問題,也是大氣污染物PM 2.5(粒徑小于2.5微米的固態(tài)顆粒)的成因之一,因此研發(fā)一種快速、穩(wěn)定、可靠的N02氣體傳感器具有重要的現(xiàn)實意義。n型寬禁帶半導體材料,如三氧化鎢(W03),被認為是高效氣敏材料,在檢測N02氣體方面表現(xiàn)出巨大的應用潛力。本文采用大氣等離子噴涂(APS)、溶液前驅(qū)體等離子噴涂(SPPS)和復合等離子噴涂(APS+SPPS)三種工藝方法,以WO3粉末和鎢酸銨水溶液作為噴涂原料沉積W03單個粒子和涂層,研究噴涂工藝參數(shù)(基體溫度、噴涂距離和氫氣流量)對單個粒子和涂層微觀結(jié)構(gòu)的影響規(guī)律,最后對W03的N02氣敏性能進行評價與分析。首先,對比APS和SPPS兩種工藝,研究基體溫度和噴涂距離對單個粒子沉積形貌的影響。實驗結(jié)果表明,基體未預熱時,APS粒子飛濺嚴重;隨著基體溫度的增加,微米粒子形貌從飛濺狀向圓盤狀轉(zhuǎn)變,轉(zhuǎn)變溫度在200℃左右。對于SPPS納米粒子而言,形貌更加復雜�；w溫度為200℃時,出現(xiàn)泡沫狀顆粒;當基體溫度為250℃時,出現(xiàn)中空球狀沉積粒子。隨后,研究了噴涂距離和氫氣流量對沉積粒子的影響規(guī)律,實驗結(jié)果顯示,噴涂距離為100 mm,氫氣流量為4 L/min時,粒子的扁平化程度最好。然后,采用三種工藝,在帶有金電極的氧化鋁(A1203)傳感器基體上制備了 W03涂層。掃描電鏡分析發(fā)現(xiàn),所有W03涂層都呈多孔、層狀特征,其中SPPS涂層孔隙率最高,APS涂層最低,APS+SPPS涂層居中。經(jīng)研究發(fā)現(xiàn),APS制備WO3涂層毛孔粗大,涂層由微米粒子堆積而成;SPPS制備W03涂層毛孔細小,涂層比表面積大;APS+SPPS具有獨特的微觀形貌,在粗大的微米級W03粒子表面附著許多納米級W03顆粒,形成獨特的微納結(jié)構(gòu)。最后,對三種涂層進行氣敏測試。結(jié)果顯示,SPPS涂層靈敏度最高,APS靈敏度最低。這是因為SPPS涂層呈現(xiàn)多孔結(jié)構(gòu),且比面積最高。涂層形貌對氣敏性能有重要影響,當采用SPPS沉積涂層時,噴涂距離為100 mm時,涂層氣敏性能最佳;當采用APS+SPPS沉積涂層,氫氣流量為2 L/min時,涂層靈敏度最佳。本文還測試了傳感器工作溫度和環(huán)境濕度對靈敏度的影響規(guī)律,當工作溫度從150℃增加到250℃時,所有試樣靈敏度均呈下降趨勢,但響應恢復時間縮短;環(huán)境濕度從0%增加到100%時,傳感器的基準電阻降低,但靈敏度變化卻較為復雜。
[Abstract]:Nitrogen dioxide (NO2) is a typical atmospheric pollutant, which can cause environmental problems such as photochemical smog and acid rain. It is also one of the causes of atmospheric pollutant PM 2.5 (solid particles with particle size less than 2.5 microns). Therefore, it is of great practical significance to develop a fast, stable and reliable N02 gas sensor. Tungsten trioxide (W03) is considered as a highly efficient gas sensitive material. It has great potential in detecting N02 gas. In this paper, three process methods, atmospheric plasma spraying (APS), solution precursor plasma spraying (SPPS) and composite plasma spraying (APS + SPPS), were used to deposit single W03 with WO3 powder and ammonium tungstate aqueous solution as spraying materials. The influence of spraying parameters (substrate temperature, spraying distance and hydrogen flow rate) on the microstructure of single particle and coating was studied. Finally, the gas sensitivity of W03 N02 was evaluated and analyzed. Firstly, the influence of substrate temperature and spraying distance on the deposition morphology of single particle was studied by comparing APS with SPPS. The results showed that APS particles splashed seriously when the substrate was not preheated, and the morphology of micron particles changed from splashing to disc with the increase of substrate temperature, and the transition temperature was about 200. For SPPS nanoparticles, the morphology was more complex. Foam particles appeared when the substrate temperature was 200, and hollow spheres appeared when the substrate temperature was 250. Subsequently, the effects of spraying distance and hydrogen flow rate on the deposition particles were studied. The experimental results showed that the flattening degree of the particles was the best when the spraying distance was 100 mm and the hydrogen flow rate was 4 L/min. Then, W03 coating was prepared on the aluminum oxide (A1203) sensor substrate with gold electrode by three processes. Microscopic analysis showed that all W03 coatings were porous and layered, of which the porosity of SPPS coating was the highest, APS coating was the lowest, and APS + SPPS coating was the middle. The results show that the SPPS coating has the highest sensitivity and the APS sensitivity is the lowest. This is because the SPPS coating has the porous structure and the highest specific area. When the spraying distance is 100 mm and the hydrogen flow rate is 2 L/min, the gas sensitivity of the coating is the best. The influence of working temperature and ambient humidity of the sensor on the sensitivity is also tested. Sensitivity is decreasing, but response recovery time is shortened. When ambient humidity is increased from 0% to 100%, the reference resistance of the sensor decreases, but the change of sensitivity is more complex.
【學位授予單位】：揚州大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TP212
本文編號：2214682
[Abstract]:Nitrogen dioxide (NO2) is a typical atmospheric pollutant, which can cause environmental problems such as photochemical smog and acid rain. It is also one of the causes of atmospheric pollutant PM 2.5 (solid particles with particle size less than 2.5 microns). Therefore, it is of great practical significance to develop a fast, stable and reliable N02 gas sensor. Tungsten trioxide (W03) is considered as a highly efficient gas sensitive material. It has great potential in detecting N02 gas. In this paper, three process methods, atmospheric plasma spraying (APS), solution precursor plasma spraying (SPPS) and composite plasma spraying (APS + SPPS), were used to deposit single W03 with WO3 powder and ammonium tungstate aqueous solution as spraying materials. The influence of spraying parameters (substrate temperature, spraying distance and hydrogen flow rate) on the microstructure of single particle and coating was studied. Finally, the gas sensitivity of W03 N02 was evaluated and analyzed. Firstly, the influence of substrate temperature and spraying distance on the deposition morphology of single particle was studied by comparing APS with SPPS. The results showed that APS particles splashed seriously when the substrate was not preheated, and the morphology of micron particles changed from splashing to disc with the increase of substrate temperature, and the transition temperature was about 200. For SPPS nanoparticles, the morphology was more complex. Foam particles appeared when the substrate temperature was 200, and hollow spheres appeared when the substrate temperature was 250. Subsequently, the effects of spraying distance and hydrogen flow rate on the deposition particles were studied. The experimental results showed that the flattening degree of the particles was the best when the spraying distance was 100 mm and the hydrogen flow rate was 4 L/min. Then, W03 coating was prepared on the aluminum oxide (A1203) sensor substrate with gold electrode by three processes. Microscopic analysis showed that all W03 coatings were porous and layered, of which the porosity of SPPS coating was the highest, APS coating was the lowest, and APS + SPPS coating was the middle. The results show that the SPPS coating has the highest sensitivity and the APS sensitivity is the lowest. This is because the SPPS coating has the porous structure and the highest specific area. When the spraying distance is 100 mm and the hydrogen flow rate is 2 L/min, the gas sensitivity of the coating is the best. The influence of working temperature and ambient humidity of the sensor on the sensitivity is also tested. Sensitivity is decreasing, but response recovery time is shortened. When ambient humidity is increased from 0% to 100%, the reference resistance of the sensor decreases, but the change of sensitivity is more complex.
【學位授予單位】：揚州大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TP212
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