Research on processing and mechanical properties of Al2O3/3Y-TZP

本研究主要是以混煉方式，製備具有塑性之複合陶瓷胚料 (Al2O3/3Y-TZP)，探討不同添加劑及混練順序對胚體流變行為、微結 構均勻度與燒結體機械性質之影響。利用扭矩流變儀及毛隙流變儀觀 察胚體之流變性質，後續燒結體微結構由掃描式電子顯微鏡觀察，並 對雙相微結構之均勻度定量化分析。實驗結果顯示複合添加劑 (Darvan C+Glycerol)能提升關鍵胚體固含量到57.4 vol%，且在A3 混 練順序下，胚料能吸收較多捏煉能量，打散胚體內聚結，使雙相複合 材料顯示較佳結構分布，且具有較窄的粒徑分佈。在胚料含有2 wt% 黏結劑以上，降伏強度即大於0.24 MPa，另添加乾燥控制劑之甲醯 胺及高比表面積之γ-Al2O3 後，能降低胚料流動指數低於0.3，單位時 間面積內水分散失率低於0.02 g/h*cm2，提升塑性指標達3.7%。 K-A3(A70Z)胚體以1600OC，持溫1 小時燒結，結果顯示燒結相對密 度為98.2%，平均破壞強度382 MPa，韋伯模數7.2，主要缺陷為大 型氣泡及氧化鋁聚結。 研究第二部份是採用膠粒製程，用以提升雙相燒結體微結構均勻 度及移除內部缺陷。實驗結果顯示，C-A70Z 以1550OC，持溫1 小時 燒結達相對密度99.9%，其四點彎曲破壞強度為551 MPa，韋伯模數 為14.5。但在氧化鋯添加量較少之C-A85Z，其四點彎曲破壞強度656 及韋伯模數15.1 皆高於C-A70Z。 在兩種不同氧化鋯添加量下，複合材料之磨耗機制由原本脆性破 壞轉為部份延性破壞，在荷重42 N 及磨耗速率0.63 m/s 下，C-A70Z 具有最佳磨耗率7.2×10-8 cm3/Nm。In this research, the ceramic feedstocks (Al2O3/3Y-TZP) were prepared by kneading of plastic formations. The effects of different additives and kneading sequences to rheological behavior, degree of homogeneity and mechanical properties of the feedstocks were investigated. The rheological properties of the feedstock were analyzed by the torque rheomerty, capillary rheometer. After sintering at suit temperatures of ≦1600OC, the two-phase microstructure was quantitatively analyzed by optical and scanning electron microscopy. The results showed that the component additives (Darvan C+Glycerol) could increase critical solid loading of feedstock to 57.4 vol%. The kneading sequence (A3) could input more shear-energy to break-up agglomeration in the feedstocks. The particles with narrow size distribution and good dispersion were optimized in the A3 kneading sequence. The yield stress of feedstock was greater than 0.24 MPa with 2 wt% PVA binder. The addition of the dry agent (formamide) and γ-Al2O3 with high surface area could control the water evaporation rate lower than 0.02 g/h*cm2, lower the flow exponent than 0.3, and increase the plastic index to 3.7%. The relative sintered density of K-A3 (A70Z) reached 98.2% T.D. as sintered at 1600OC for 1 hr. The four-point bending strength of K-A3 was 382 MPa with lower Weibull modulus 7.2. The major fracture origins are large air bubbles and Al2O3 agglomerates. The second part of this research was adopted colloidal process to increase the degree of homogeneity of composite microstructure and control the flaw size distribution. The results showed the relative sintereddensity of C-A70Z reached 99.9% T.D. as sintered at lower temperature 1550OC for 1 hr. The four-point bending strength of C-A70Z was 551 MPa and Weibull modulus 14.5. For C-A85Z with a lower ZrO2 content (15 vol%), the average bending strength 656 MPa and Weibull modulus 15.1 were obtained. At different volume ratio of ZrO2 content, the wear mechanism of the composite will changed from severe brittle fracture (15 vol%) to plastic deformation (30 vol%) at an applied normal load of 42N and a sliding velocity of 0.63 m/s. The best wear resistance rate of 7.2×10-8 cm3/Nm was noted in C-A70Z.目錄 第一章 前言.........................................................................................- 1 - 第二章 文獻回顧.................................................................................- 2 - 2.1 氧化鋁及氧化鋯特性.............................................................- 2 - 2.1.1 複合材料.......................................................................- 6 - 2.2 陶瓷膠粒製程......................................................................- 9 - 2.2.1 膠粒表面電位..........................................................- 11 - 2.2.2 複合粉體對IEP 點的影響......................................- 17 - 2.3 塑性成型............................................................................- 19 - 2.3.1 混煉及扭矩特性......................................................- 22 - 2.3.2 胚料流變行為..........................................................- 26 - 2.3.3 擠出..........................................................................- 27 - 2.4 氧化鋯氧化鋁複合材料之機械性質...................................- 29 - 2.4.1 機械強度與微結構及缺陷之間的關係.....................- 34 - 2.4.2 磨耗性質.....................................................................- 38 - 第三章 實驗步驟...............................................................................- 43 - 3.1 實驗設計...............................................................................- 43 - 3.2 實驗材料...............................................................................- 44 - 3.2.1 陶瓷粉體.....................................................................- 44 - 3.2.2 高分子塑性劑.............................................................- 44 - 3.3 實驗流程...............................................................................- 44 - 3.4 性質分析...............................................................................- 50 - 3.4.1 粉末比表面積之量測.................................................- 50 - 3.4.2 粉末表面電位( -potential)測量...............................- 50 - 3.4.3 漿料之粒徑量測.........................................................- 51 - 3.4.4 扭矩流變儀.................................................................- 51 - 3.4.5 黏度測試.....................................................................- 52 - 3.4.6 密度量測.....................................................................- 54 - 3.4.7 樣品塑性性質測試.....................................................- 55 - 3.4.8 樣品乾燥試驗.............................................................- 56 - 3.4.9 X-ray 繞射晶相分析...................................................- 56 - 3.4.10 掃描式電子顯微鏡(SEM)觀察樣品之微結構........- 56 - 3.4.11 晶粒大小量測及均勻度分析...................................- 57 - 3.4.12 強度測試...................................................................- 58 - 3.4.13 硬度及韌性質量測...................................................- 59 - 3.4.14 磨耗測試...................................................................- 62 - 第四章 結果.......................................................................................- 63 - 4.1 混煉順序對胚料性質影響...................................................- 63 - 4.1.1 界面劑對胚料影響.....................................................- 63 - 4.1.2 不同混煉順序對扭矩曲線的影響..............................- 67 - 4.1.3 不同混煉順序對微結構均勻度的影響.....................- 73 - 4.2 塑性成形製程.......................................................................- 78 - 4.2.1 黏結劑對胚料塑性之影響.........................................- 78 - 4.2.2 乾燥控制劑對胚料性質之影響.................................- 84 - 4.2.3 -氧化鋁對胚料之影響............................................- 89 - 4.3 膠體行為...............................................................................- 94 - 4.3.1 分散劑用量之影響......................................................- 94 - 4.3.2 混合分散時間之影響.................................................- 98 - 4.3.3 溫度、時間對燒結緻密化的影響...........................- 102 - 4.3.4 膠粒製程對微結構之均勻度影響...........................- 111 - 4.4 複合材料之機械性質.........................................................- 115 - 4.4.1 破壞強度及破壞源分析...........................................- 115 - 4.4.2 複合材料之硬度及韌性值.......................................- 134 - 4.4.3 複合材料之磨耗性質...............................................- 138 - 第五章 討論.....................................................................................- 147 - 5.1 消耗能量對胚料均勻度之影響.........................................- 147 - 5.2 胚料流變行為對塑性指標之影響.....................................- 153 - 5.3 晶粒大小與相轉換對強度的影響.....................................- 158 - 第六章 結論.....................................................................................- 165 - 參考文獻...........................................................................................- 168