精密氧化鋯射出胚料性質及其強度性質之研究
| Autor: | Rong-Yuan Wu, 吳榮源 |
|---|---|
| Rok vydání: | 2004 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 92 The process of ceramic injection molding consisted of kneading process, injection molding, debinding process and sintering process. In my study, feedstock homogeneity and physical properties of Mg-PSZ and 3Y-TZP is investigated for fabricating precise parts by micro-injection molding. The objectives of my research include: 1. How to select best appropriate surfactant is selected for get stable feedstock and best physical properties of injection parts. 2. How to quantitatively analysis technique of feedstock homogeneity is established. The relationship between feedstock homogeneity and kneading power is realized by power consumption diagram. 3. According to power consumption relationship the torque variation of feedstock is monitored by torque rheometer. The relationship between feedstock homogeneity and kneading time is analyzed to get appropriate kneading process. 4. The different zirconia feedstock is kneading and pelleting by kneaders. The feedstock homogeneity that is relative to dimensional stability and fracture strength of sintering part is observed. Firstly, according to Lewis acid-base theory the appropriate surfactant is selected to get the stability of Mg-PSZ feedstock. The sedimentation behavior of solvents and melted waxes is observed by adding different surfactants. The flow properties of zirconia feedstocks are measured by torque and capillary rheometer. Then, the dimensional stability and fracture strength of sintering properties is observed the relationship of surfactant types. The zirconia suspension contained F1 surfactant of ester group get dispersive behavior in heptane or melted wax. The F1 surfactant improved wetting effect with zirconia and increased viscosity of Mg-PSZ feedstock. The zirconia feedstock that made up of F1/ SA duplex surfactants become more stability of flow properties and smallest variation of physical properties. Secondly, the homogeneity of zirconia feedstock is analyzed quantitatively by torque rheometer, capillary rheometer and transmission optic microscopy. The quantitative indexes have homogenous index (Ha) and dispersive index (Ds). The dispersive index shows significantly feedstock homogeneity. Besides, calculating the power consumption diagram (Np-Re diagram) is due to torque variation of kneading process. The parameters of kneading power, Reynolds number are calculated with kneading temperature and speed of blade rotation. The kneading power (P) that calculated from Np-Re equation is critical value with feedstock homogeneity. Thirdly, the kneading behavior of 3Y-TZP feedstock is investigated by torque rheometer and transmission optic microscopy. The optimum kneading process is determined to fully homogenous feedstock due to the relationship between feedstock homogeneity and kneading time. The physical properties of sintering parts are analyzed for injection molding, debinding and sintering. The different kneading conditions are selected to knead zirconia feedstock. The agglomerate fraction in feedstock is relative to kneading curve that involved temperature, rotation and time. The best kneading curve of 170oC/30 rpm/60 min and then 150oC/30 rpm/90 min fabricates zirconia feedstock that contained less than 1% agglomerate. The ceramic parts are fabricated from zirconia feedstock by the processes of injection molding, debinding and sintering. The dimensional stability and fracture strength of sintering parts are increased. Finally, homogenous feedstock of zirconia is made up by Z-blade kneader with best distributive mixing, twin roller kneader and torque rheometer with dispersive mixing. The dispersive index of 3Y-TZP feedstock is 0.81 due to kneading by Z-blade kneader. Then, the dispersive index is less than 2% agglomerate due to kneading by two roller mixer or torque rheometer. The shear stresses of twin roller kneader and torque rheometer are 50 kPa and 9.6 kPa, respectively. The kneading time of twin roller kneader needs less than torque rheometer. The homogenous feedstock is fabricated to injection parts. The dimensional variation of sintering parts that made up homogenous feedstock is less than 0.1 % and fracture strength improves from 520 to 780 MPa. The Weibull modulus increase from m=8 to m=12. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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