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氧化鋁陶瓷目前分為高純型與普通型兩種。氧化鋁陶瓷干壓成型技術于形狀單純且內(nèi)壁厚度超過1mm,長度與直徑之比不大于4∶1的物件。由于液壓式壓機沖程壓力均勻,故在粉料充填有差異時壓制件高度不同。而機械式壓機施加壓力大小因粉體充填多少而變化,易導致燒結后尺寸收縮產(chǎn)生差異,影響產(chǎn)品質(zhì)量。
注漿成型是氧化鋁陶瓷使用早的成型方法。由于采用石膏模、成本低且易于成型大尺寸、外形復雜的部件。注漿成型的關鍵是氧化鋁漿料的制備。通常以水為熔劑介質(zhì),再加入解膠劑與粘結劑,充分研磨之后排氣,然后倒注入石膏模內(nèi)。由于石膏模毛細管對水分的吸附,漿料遂固化在模內(nèi)。空心注漿時,在模壁吸附漿料達要求厚度時,還需將多余漿料倒出。
將顆粒狀陶瓷坯體致密化并形成固體材料的技術方法叫燒結。燒結即將坯體內(nèi)顆粒間空洞排除,將少量氣體及雜質(zhì)有機物排除,使顆粒之間相互生長結合,形成新的物質(zhì)的方法。
連續(xù)熱壓燒結雖然提高產(chǎn)量,但設備和模具費用太高,此外由于屬軸向受熱,制品長度受到限制。熱等靜壓燒成采用高溫高壓氣體作壓力傳遞介質(zhì),具有各向均勻受熱之優(yōu)點,很適合形狀復雜制品的燒結。由于結構均勻,材料性能比冷壓燒結提高30~50%。比一般熱壓燒結提高10~15%。
有些氧化鋁陶瓷材料在完成燒結后,由于氧化鋁陶瓷材料硬度較高,需用更硬的研磨拋光磚材料對其作精加工。通常采用由粗到細磨料逐級磨削,終表面拋光。此外激光加工及超聲波加工研磨及拋光的方法亦可采用。有些氧化鋁陶瓷零件需與其它材料作封裝處理。(圖/文tujian.net.cn)
中譯英:
Alumina ceramics are divided into high purity type and ordinary type two. Alumina ceramic dry press forming technology is limited to the shape and the inner wall thickness more than1mm alone, the length and diameter ratio greater than 4: 1. As the hydraulic press stroke uniform pressure, so the powder filling there are differences when pressing different height. Mechanical type compressor pressure size because of the powder filling much change, easily lead to sintering shrinkage difference, affect the quality of the product.
Injection molding is the earliest use of alumina ceramic forming method. Due to the adoption of the gypsum mold, low cost and easy forming of large size, the shape of complex parts. Injection molding is the key of alumina slurry preparation. Usually in water flux as medium, adding solution of glue and adhesive after grinding, fully exhaust, then pour into the gypsum mould. As a result of plaster mold capillary water absorption, slurry and solidification in mould.