發(fā)布時間：2018-05-08 07:09

  本文選題：注射成型 + 大分子粘結(jié)劑��； 參考：《北京科技大學》2017年博士論文

【摘要】：與其他傳統(tǒng)的成型技術相比,陶瓷注射成型(CIM)具有原材料利用率高、機械化程度高、特別適于大規(guī)模生產(chǎn)體積小、形狀復雜、尺寸精度高等元件的優(yōu)點,使其在高效制備復雜形狀陶瓷部件領域得以廣泛應用。有機粘結(jié)劑作為其工藝流程中重要一環(huán)將直接影響CIM制品的性能;然而目前常用的粘結(jié)劑體系存在喂料均勻度差(聚乙二醇粘結(jié)劑體系喂料易發(fā)生粘結(jié)劑偏析)、脫脂階段易對環(huán)境產(chǎn)生污染(石蠟基粘結(jié)劑體系脫脂常使用有毒性溶劑)等問題。鑒于環(huán)保及喂料均勻度考慮,本論文一方面以石蠟基粘結(jié)劑體系為研究對象,采用無毒性溶劑(煤油)脫除粘結(jié)劑,從大分子粘結(jié)劑類型、粘結(jié)劑組成角度,確定最適于煤油萃取脫脂的大分子粘結(jié)劑及獲得性能優(yōu)異CIM制品的粘結(jié)劑配比;另一方面以聚乙二醇基水溶性粘結(jié)劑體系為研究對象,針對粘結(jié)劑偏析的問題,從粉體及粘結(jié)劑角度展開研究。本論文首先研究了不同類型(單相/復相)大分子粘結(jié)劑對注射成型氧化鋯陶瓷性能的影響,發(fā)現(xiàn)復相大分子粘結(jié)劑的使用可使注射喂料更為均勻;混合使用高密度聚乙烯(HDPE)和低密度聚乙烯(LDPE)大分子粘結(jié)劑的坯體經(jīng)煤油萃取后氣孔均勻、細小,經(jīng)燒結(jié)后展現(xiàn)出很高的致密度(相對密度98.9%)及優(yōu)異的力學性能(抗彎強度949MPa),表明L/H粘結(jié)劑體系更適于氧化鋯陶瓷的注射成型。粘結(jié)劑組成是影響注射喂料均勻度的內(nèi)部因素。研究表明,合理調(diào)控粘結(jié)劑組成比例可使粘結(jié)劑最大程度填充于陶瓷顆粒之間,最終提高喂料的均勻度;通過直接及間接方法推測出均勻喂料的粘結(jié)劑組成,通過燒結(jié)后性能對比進一步驗證了幾種均勻度判定法的準確性。粘結(jié)劑偏析是聚乙二醇基水溶性粘結(jié)劑體系廣泛應用的阻礙,從粉體角度來看,喂料粘結(jié)劑偏析是由納米陶瓷顆粒易團聚及與粘結(jié)劑相容性差引起的;采用球磨預改性引入油酸可明顯改善這一情況,研究表明油酸可通過酯化或離子交換反應吸附在氧化鋯顆粒表面,形成一層無定形膜,改變粉體表面極性,從而減少團聚,得到均勻、缺陷少的喂料,氣孔分布集中的脫脂素坯,且在燒結(jié)后展現(xiàn)出優(yōu)異的力學性能及致密度。從粘結(jié)劑角度來看,喂料粘結(jié)劑偏析是由聚乙二醇結(jié)晶溫度與聚甲基丙烯酸甲酯玻璃化溫度差異過大,由聚乙二醇收縮產(chǎn)生的不一致收縮引起的;采用引入適量聚乙烯吡咯烷酮的方法可減少粘結(jié)劑偏析引發(fā)的缺陷,研究表明聚乙烯吡咯烷酮的引入可有效抑制聚乙二醇的結(jié)晶,提高生坯均勻度,降低熱脫后坯體氣孔尺寸,促進燒結(jié)致密化進行,顯著減少燒結(jié)缺陷及提高燒結(jié)體力學性能。
[Abstract]:Compared with other traditional molding technologies, ceramic injection molding (CIM) has the advantages of high utilization of raw materials, high degree of mechanization, especially suitable for large scale production of small volume, complex shape, high dimensional precision and so on. It has been widely used in the field of efficient preparation of complex shape ceramic components. As an important part of the process, organic binder will directly affect the properties of CIM products. However, the commonly used binder system has some problems such as poor feed uniformity (the segregation of binder is easy to occur in the feed system of polyethylene glycol binder system, and the environment is easily polluted in degreasing stage (toxic solvent is often used in degreasing of paraffin based binder system). In view of environmental protection and feed uniformity, on the one hand, in this paper, paraffin based binder system was studied, nontoxic solvent (kerosene) was used to remove binder, from the point of view of the type of macromolecular binder and the composition of binder, The macromolecular binder that is most suitable for kerosene extraction and degreasing and the ratio of binder for obtaining excellent performance CIM products are determined. On the other hand, the water soluble binder system based on polyethylene glycol is taken as the research object, aiming at the problem of binder segregation. The study was carried out from the point of view of powder and binder. In this paper, the effects of different kinds of macromolecular binders on the properties of zirconia ceramics were studied. It was found that the use of multiphase macromolecular binders could make the injection feeding more uniform. The billet with high density polyethylene (HDPE) and low density polyethylene (LDPE) binder was extracted by kerosene and its porosity was uniform and fine. After sintering, high densification (relative density 98.9) and excellent mechanical properties (bending strength 949 MPA) showed that the L / H binder system was more suitable for the injection molding of zirconia ceramics. The composition of binder is the internal factor that affects the uniformity of injection feed. The results show that reasonable control of the proportion of binder can make the binder fill the ceramic particles to the maximum extent, and finally improve the uniformity of the feed, the binder composition of the uniform feed can be inferred by direct and indirect methods. The accuracy of several homogeneity determination methods is further verified by the comparison of sintering performance. The segregation of binder is an obstacle to the wide application of water-soluble binder system based on polyethylene glycol. From the point of view of powder, the segregation of binder is caused by the agglomeration of nano-ceramic particles and the poor compatibility with binder. It was found that oleic acid could be adsorbed on the surface of zirconia particles by esterification or ion exchange reaction, forming an amorphous film, changing the polarity of powder surface and reducing agglomeration. The degreasing billets with uniform feed, less defects and concentrated pore distribution were obtained, and the excellent mechanical properties and densification were obtained after sintering. From the point of view of binder, the segregation of feed binder is caused by the excessive difference between the crystallization temperature of polyethylene glycol and the glass transition temperature of poly (methyl methacrylate), and the inconsistent shrinkage caused by the shrinkage of polyethylene glycol. The method of introducing proper amount of polyvinylpyrrolidone can reduce the defects caused by the segregation of binder. The results show that the introduction of polyvinylpyrrolidone can effectively inhibit the crystallization of polyethylene glycol, increase the evenness of green, and reduce the pore size of green body after thermal desorption. Promote sintering densification, reduce sintering defects and improve sintering physical properties.
【學位授予單位】：北京科技大學
【學位級別】：博士
【學位授予年份】：2017
【分類號】：TQ174.62;TQ430.1

【參考文獻】

相關期刊論文 前4條

1 Xian-feng Yang;Jiang-hong Yang;Xie-wen Xu;Qi-cheng Liu;Zhi-peng Xie;Wei Liu;;Injection molding of ultra-fine Si_3N_4 powder for gas-pressure sintering[J];International Journal of Minerals Metallurgy and Materials;2015年06期

2 楊現(xiàn)鋒;謝志鵬;賈翠;劉偉;劉其城;;陶瓷注射成型充模過程及成型缺陷計算機模擬分析[J];稀有金屬材料與工程;2011年S1期

3 ;Influence of the Compacts Homogeneity on the Incidence of Cracks during Thermal Debinding in Ceramic Injection Molding[J];Journal of Materials Science & Technology;2009年02期

4 鄭振興;夏偉;周照耀;朱權利;;Numerical simulation of tungsten alloy in powder injection molding process[J];Transactions of Nonferrous Metals Society of China;2008年05期

，

本文編號：1860445