近年來，毫微米級氧化鋁陶瓷製程及性質受到格外的重視，但毫微米 a 氧化鋁在燒結過程之中，易造成晶粒過度的成長，進而改變其期待之性質與降低利用性。是故，有系統的瞭解 a 氧化鋁粉末的成型與燒結行為，將是毫微米級陶瓷製程上之一大課題。本實驗就是想瞭解微米與毫微米級的 a 氧化鋁粉末在成型階段的異同，並在成型後控制相同變因下，燒結緻密化的過程有什麼不同的演變，藉此更瞭解因為不同粒徑分佈與凝聚狀態所主導的 a 氧化鋁結構陶瓷製程。
　　本實驗採用微米與次微米之 a-Al2O3 三批粉末 (1.8 (L), 0.43 (M), 0.15 mm (S)) 為起始原料，起始粉末過 200 目篩後，以三種不同成型壓力 (10, 70, 600 MPa) 進行單軸乾壓以固定其生坯相對體密度 55%，來製成生坯。以 MTS、孔隙儀、熱膨脹儀與 SEM 進行粉末壓密分析、生坯孔隙大小及分佈分析、燒結收縮分析與微結構觀察並比較其成型特性，再經過 1000℃ 至 1700℃ 不持溫之熱處理得到氧化鋁燒結體，最後量測其相對視密度、孔隙大小及分佈，並透過微結構觀察來綜合比較其燒結行為。
　　研究發現在生坯成型階段上，一次粒子粒徑與分佈最大的粉末 1.8 mm (L)，因為大小顆粒之間的堆疊，縱使在沒有經過造粒步驟及流動性與粒子外型均不佳的情況下，在壓實過程中也易達成緊密堆積，而其相對體密度為三批粉末中最高。在本研究中，顆粒粒徑對成型沒有影響，而是在顆粒分佈 (一次粒子或凝聚體)，分佈愈廣，愈利於成型；所造粒成的軟凝聚體外型愈成球型 (流動性佳)、且其強度愈弱與分佈愈廣也愈利於成型。在燒結階段上，三批燒結體中，0.43 mm (M) 因為本身硬凝聚體的存在，所以最先開始燒結收縮 (1100℃)，整體收縮呈現不均勻情形 (多指狀燒結現象)，0.15 mm (S) 因為在燒結前 (1300℃) 發生粒子重排，所以會比 (M) 來得晚開始燒結收縮，一旦整體粒子與孔隙空間分配得更為均勻後，其收縮就比其他兩批來得均勻且速率最快。顆粒粒徑愈小且分佈愈集中處愈利於燒結，而粒徑差異過大的顆粒，雖然利於成型但卻不利於燒結發生；顆粒外型愈均一、分佈愈窄且無硬凝聚粒子，晶粒異常成長就愈不易發生。

　　It has paid much attention to the process and property of sub-micron alumina ceramics recently. But it is easy to accompany with excessive grain growth of sub-micron alpha-alumina during sintering. That will change the expectant property and reduce the application. Therefore, it will turn into the topic of sub-micron ceramics processes with realizing the forming and sintering behavior of alpha-alumina systematically. This study hopes to understand the difference of forming of nano-meter and sub-meter alpha-alumina powder, and understand the densification development when sintering after the forming then got the same factors. It can also understand the alpha-alumina structure ceramics process resulted from different particle size distribution and agglomeration.
　　The starting materials used in the study were 1.8, 0.43, and 0.15 mm alpha-phase, micron and sub-micron alumina powders. After the sieving with number 200 followed by the cylindrical pellets were prepared and fixed in green compact relative bulk density 55% derived from three different pressure with 10, 70, and 600 mega-pascal (MPa) when forming with automatic uniaxial hydraulic press. After the analyses of powder compaction , green body pore size distribution, sintering shrinkage, and micro-structure observation with Material Test System (MTS), porosimetry, dilatometer, and scanning electron microscope (SEM) followed by comparing the characteristics of forming. Then the green body were heated from 1000℃ to 1700℃. After the above heat treatment, the measurement of relative apparent density and pore size distribution and micro-structure evolution observation were used to compare the whole sintering behavior.
　　In this research of forming stage: Although there was no granulating step, low flow ability and irregular particle morphology, the 1.8 mm (L) powder with biggest primary particle size and broadest distribution was easy to get the closest packing when forming resulted from the packing of different size of particles. And the relative bulk density is most all over powders in the study. Instead of the affection of particle size in the study, the more wide particle distribution (primary particles or agglomerates), the more beneficial when forming. And the more uniform soft agglomerates’ morphology like ball shape (high flow ability), low granular strength, and wide particle distribution from granulating, the more beneficial when forming, too; At the sintering stage: The 0.43 mm (M) powder has hard agglomerates itself, so it took precedence over the others in sintering (1100℃). But during sintering, the bulk shrinkage showed a abnormal presentation (like finger grain growth). The sintering of 0.15 mm (S) powder began behind (M) but it was regular after the particle and pore rearrange in space (1300℃). So the shrinkage regularity and rate were excellent all over others. The more small particle size section and narrow particle distribution, the more beneficial when sintering. The more different particle size, the more beneficial when forming but impedimental when sintering. The more uniform particle morphology, narrow particle size distribution, and have no hard agglomerates, the less abnormal grain growth when sintering.

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