【作者】 王鹤錕；

【导师】 雅菁；

【作者基本信息】 天津城市建设学院 ， 材料学， 2009， 硕士

【摘要】 本文以质量分数95%的Al2O3,5%的CaO-Al2O3-SiO2的粉体为研究对象,系统研究了氧化铝注射成型所涉及的喂料制备、注射成型以及脱脂等工艺过程。论文研究了适合注射成型的95氧化铝粉体和石蜡-聚烯烃粘结剂体系,并对粘结剂组元的相容性进行了判断。系统讨论了喂料的固相体积分数对注射成型坯体、烧结体力学性能的影响,结果表明:当固相体积分数为59vol%时,脱脂后的试样有比较明显的塌陷现象,烧结体的密度为3.58g/cm3,抗弯强度为250.37MPa。当固相体积分数为70vol%时,脱脂后试样完好,烧结体的密度为3.73g/cm3,抗弯强度为290.56MPa。系统讨论了粘结剂配方对氧化铝喂料成形性和流动性的影响,实验结果表明,粘结剂中相对石蜡含量的增加有助于提高喂料的均匀性,降低喂料的粘度。但由于粘结剂体系中起支撑作用的骨架高聚物含量降低,从而使成型出来的素坯强度会随之下降,并且会进一步影响到烧结后样品的致密度。优化后的实验所用的粘结剂体系配方为72wt%PW-8wt%PP-8wt%VAE- 8wt%DBP-4wt%SA。论文研究了注射参数对成形坯体的影响,特别是对坯体质量影响较大的两个重要参数(注射温度和注射压力)进行了系统的研究,结果表明:当注射压力为50MPa时,坯体产生凹陷现象;当注射压力为100MPa时,坯体内部容易形成较大的残余应力和应力集中,烧结体出现弯曲的现象。因此在保证充模完整的情况下应尽量减小注射压力。当注射温度为120℃-100℃-100℃-100℃-70℃时,会导致喂料充模不满;当注射温度为180℃-150℃-150℃-150℃-70℃时,将导致喂料中低熔点有机物挥发严重,进而造成坯体结构不致密。在此基础上,确定了实验中采用的各注射参数值。论文分析了粘结剂体系中主要粘结剂组元的TGA曲线,研究发现,这种多组元构成的粘结剂体系能够将脱脂缺陷减少到最小。根据热脱脂过程和喂料的DTA/TGA曲线,制定了合理的热脱脂升温制度,讨论了固相体积分数对极限升温速率的影响,结果表明:固相体积分数越高,极限升温速率越大,因此适当提高固相体积分数,可以极大的缩短脱脂时间。针对脱脂过程中易产生的缺陷进行了分析,并提出了相应的解决措施。更多还原

【Abstract】 This thesis presents about injection molding of alumina powder. The processes involved feedstock preparation, injection molding and the followed debinding process. The major works were showed as bellow:Alumina powder and wax-polyolefin that are suitable for injection molding were studied,and the compatibility of binder system was judged. The influences of the solid loading on mechanical properties of the green and sintered parts were researched, the result shows that when the solid volume fraction is 59vol%, the debinded parts are depression, the density of sintered parts is 3.58g/cm3, the bending strength is 250.37MPa; when the solid volume fraction is 70vol%, the debinded parts are intact, the density of sintered parts is 3.73g/cm3, the bending strength is 290.56MPa. The influences of the relative proportion of binders on the homogeneity and formability of alumina feedstock was systematically discussed, The result shows that the increase of wax amount in binders helps to improve its homogeneity and decrease its viscosity. However, the increase of wax amount leads to the decrease of the polymers which play the role of skeleton in the feedstock, and results in the the density and bend strength of the feedstock decrease. The compactability of sintered ceramic will also be affected with the wax amount increase. the proportion of binders is 72wt%PW-8wt%PP-8wt%VAE- 8wt%DBP-4wt%SAThe influences of injection press and injection temperature on qualities of green were discussed. the result shows that when the injection press is 50MPa,the green is depression, when the injection press is 100MPa,which easily led to residual stress and stress concentration in the green, thus, injection pressure should reduce when die is complete. when the injection temperature is 120℃-100℃-100℃-100℃-70℃, feedstock will be not complete die; when the injection temperature is 180℃-150℃-150℃-150℃-70℃, which result in the volatile of the organic of low melting in the feedstock, and then sintered structure is not compactability. On these basis, the parameters used in the experiment are fixed.The TGA of binders are respectively analyzed, binder system which is builded up by multi-crew binder helps to reduce defects. The reasonable procedure of thermal debinding was designed according to DTA/TG.A and thermal debinding process. The influences of the solid volume fraction on the velocity of heating were studied, the velocity of heating increase with the solid volume fraction were increased. Therefore, appropriately increasing the solid volume fraction, the time of debinding can be shorten. The solution can be proposed according to defects that occur easily in debinding.更多还原