離心力與模溫對碟形陶瓷射出成形品硬度的影響

Abstract

由於陶瓷材料具備堅硬、耐磨及優異的抗靜電特性，在被動元件的製程設備上大量使用陶瓷材料為模治具。陶瓷粉末射出成形(PIM)特性受到粉末固含量及黏結劑配方不同、射出成形參數設定、脫脂燒結的溫度與方法所影響，當粉末固含量高時固然可得到硬度高之製品，然而應用在薄片射出時容易因為射出胚料前端冷卻而產生短射現象，降低粉末固含量固然可使射出成形容易，硬度與強度降低卻是另一隱憂。 本實驗成功製備以離心加壓成形法應用於陶瓷射出成形中，實驗以低壓為射出壓力配合離心力的作用，將一定比例之陶瓷粉末與黏結劑經混練、射出、溶劑脫脂與燒結後得到陶瓷工件。實驗結果顯示在適當的模溫與離心力作用下，因為Al O 粉末比重比黏結劑高，當胚料射出後離心力作用於粉末時，粉末呈放射性狀態往外甩至工件的外圍。以維氏硬度機量測燒結後硬度並以受離心力作用與否比較，結果在外徑邊緣硬度約增加1.02倍，以二次元尺寸量測儀量測外徑尺寸約增加1.006倍。以掃描式電子顯微鏡觀察粉末顆粒分布狀況，內部顯微結構緻密。

ABSTRACT Because the ceramic parts possess the hardness, wear-resisting and excellent antielectrostatic characteristic. On passive component process, many ceramics parts is used on the equipment. The Powder Injection Molding characteristic is effects by solid content、binder、different injection parameters、debinding or sinter temperature. It is no doubt receive the products of high hardness when the solid content is high,but apply on injection disc parts is easy happen short shot because feedstock on molded inside is dry.It is easy injection to make disc parts if decrease solid content, but the hardness and intensity will be reduced. This experiment is successful to design and make machine that the function is combine with PIM and centrifugal force, the injection pressure is low and co-operate with centrifugal force, use ceramic powder and binder prescription to mix together and process made by mixing、injection、debinding and sinter to get ceramic parts. The experimental result reveals under proper mould's temperature and centrifugal force, because Al O powder gravity is higher than binder, so centrifugal force active on particle when feedstock injection into mould, the feedstock will spray and fill on whole mould, especially on the edge have higher pressure. After ceramic parts pass through sinter, used Vickers Hardness to measure and compare with ceramic parts which use centrifugal force or not. The result show ceramic parts under centrifugal force, on the parts edge hardness have 1.02 times than normal injection. Use instrument to measure disc diameter show the out side diameter increase 1.006 times. Use SEM to observe particle size distribution, on the edge whole used centrifugal force parts indensity is highr then normal parts.