發(fā)布時間：2018-05-07 02:31

  本文選題：梯度 + 陶瓷增強復合涂層��； 參考：《華東理工大學》2017年碩士論文

【摘要】：通過真空釬焊技術,以柔性金屬布形式制備的WC-NiCrBSi合金涂層具有許多優(yōu)點,例如涂層內(nèi)部致密,無裂紋、氣孔現(xiàn)象;涂層與基體是冶金結合,結合強度高;真空氛圍,無氧化、脫碳等污染雜質出現(xiàn);涂層表面光潔,能應用于各種曲面結構的改性等。陶瓷/金屬梯度材料因其一側具有陶瓷材料的耐磨損、硬度高、耐高溫性能,另一側具有金屬材料韌性高、強度高的優(yōu)點。因此將釬焊技術和陶瓷梯度材料的結合會有重大應用價值。本文在真空釬焊工藝下制備了梯度WC陶瓷增強的NiCrBSi合金涂層,主要的研究內(nèi)容和結果如下:對WC柔性金屬布的成型配比進行了實驗,研究發(fā)現(xiàn),mWC:mP7FE在10-150范圍內(nèi)能夠成型,當質量比小于10時,得到的金屬布彈性低,質量比大于150時,金屬布強度低易爛掉;對質量比在10-60范圍內(nèi)經(jīng)過四次折疊輥壓后的金屬布進行了拉伸性能測試,研究發(fā)現(xiàn)隨著質量比的增加斷裂應變增加,質量比大于50后,斷裂應變減小。進行了不同釬焊溫度和保溫時間下均勻WC增強的NiCrBSi合金涂層的拉伸性能和磨損性能測試,為制備梯度涂層做工藝參數(shù)方面的準備。研究發(fā)現(xiàn),當保溫時間為15min,釬焊溫度在1000-1100℃范圍變化時,在1080℃時磨損損失量最小為11.1mg;當釬焊溫度為1080℃,保溫時間在5-30min范圍時,隨著溫度的增加拉伸性能逐漸升高加后降低,在保溫時間為10℃時,涂層結合強度最高為230MPa。通過調(diào)整金屬布中WC顆粒和NiCrBSi合金粉體積比,使不同層金屬布中的合金粉體積比呈梯度變化,通過大量的實驗和釬焊工藝參數(shù)的優(yōu)化,得到四種不同梯度斜率的梯度WC增強NiCrBSi合金涂層。對四種不同梯度斜率的涂層試樣進行了磨損性能的測試,研究了涂層梯度形式對涂層微觀形貌、硬度和摩擦磨損性能的影響。隨著涂層梯度斜率的增加,涂層的耐磨性能增加。當涂層梯度斜率較小時涂層的磨損損失失效機制為磨料磨損,當梯度斜率較大時為疲勞磨損失效。對四種不同梯度斜率的涂層和涂層/基體試樣進行拉伸性能的實驗,研究涂層的斷裂機理。通過原位拉伸觀察涂層/基體試樣涂層表面裂紋從萌生到完全貫穿的全過程,發(fā)現(xiàn)裂紋萌生于WC顆粒及其附近應力集中的地方。隨著涂層梯度斜率增加,涂層/基體斷裂應變增加,貫穿裂紋數(shù)量略有增加;涂層斷裂應變減小,能承受的拉伸強度減小,涂層為脆性斷裂。
[Abstract]:Through vacuum brazing technology, WC-NiCrBSi alloy coating prepared in the form of flexible metal cloth has many advantages, such as dense coating, no crack, porosity phenomenon, metallurgical bonding between coating and substrate, high bonding strength, vacuum atmosphere and no oxidation. Pollution impurities such as decarbonization appear and the coating surface is smooth and can be used in modification of various surface structures. Ceramic / metal gradient material has the advantages of wear resistance, high hardness and high temperature resistance of ceramic material, and high toughness and strength of metal material on the other side. Therefore, the combination of brazing technology and ceramic gradient materials will have great application value. In this paper, gradient WC ceramic reinforced NiCrBSi alloy coatings were prepared by vacuum brazing. The main research contents and results were as follows: the forming ratio of WC flexible metal cloth was tested, and it was found that mWC: mP7FE could be formed in the range of 10-150. When the mass ratio is less than 10:00, the elasticity of the metal cloth is low, and when the mass ratio is greater than 150, the low strength of the metal cloth is easy to rot, and the tensile properties of the metal cloth after four fold roll pressing in the mass ratio of 10-60 are tested. It is found that the fracture strain increases with the increase of mass ratio, and decreases when mass ratio is greater than 50. The tensile and wear properties of NiCrBSi alloy coatings with uniform WC reinforcement at different brazing temperature and holding time were tested in order to prepare the process parameters for the preparation of gradient coatings. It is found that when the holding time is 15min and the brazing temperature varies from 1000-1100 鈩，

本文編號：1855013