Kamran SAMET, Oğuz YILMAZ, Harun KOÇAK, Asghar SAFARİAN, Çetin KARATAŞ

TOZ ENJEKSİYON KALIPLAMA İLE ÜRETİLMİŞ TUNGSTEN KARBÜR PARÇALARDA BAĞLAYICI GİDERME SÜRESİNİN VE PARÇA BOYUTLARININ AĞIRLIK KAYBINA ETKİSİNİN ARAŞTIRILMASI

Toz enjeksiyon kalıplama (TEK), plastik enjeksiyon kalıplama ve geleneksel toz metalürjisi tekniklerinin kombinasyonundan ortaya çıkmış bir yöntemdir. Bu metot besleme stoğunun hazırlanması, besleme stoğunun kalıba enjekte edilmesi, bağlayıcı ayrıştırma işlemi ve sinterleme olmak üzere dört temel adımdan meydana gelmektedir. TEK’te bağlayıcı ayrıştırma işlemi, sinterleme sonrasında parçada elde edilecek nihai mukavemete etki etmektedir. Aynı zamanda bağlayıcı ayrıştırma süresinin uzunluğu maliyeti arttırmaktadır. Bundan dolayı bağlayıcı ayrıştırma işlemi esnasında meydana gelen optimum ağırlık kaybının tespit edilmesi önemlidir. Bu çalışmada üç farklı kalınlıkta (4,3; 9,75 ve 12 mm) ve uzunlukta (15, 14, ve 11 mm) numuneler WC-% 9Co besleme stoğundan TEK yöntemi ile üretilmiştir. Daha sonra numuneler 24, 48, 60 ve 72 saat olmak üzere dört farklı sürede, etanol kullanılarak kimyasal bağlayıcı ayrıştırma işlemine tabi tutulmuştur. Deneyler sonucunda parçanın kalınlığı, hacmi, yüzey alanı/hacim (Ay/V) oranı ve bağlayıcı ayrıştırma süresinin ağırlık kaybına etkisi tespit edilmiştir. Çalışma sonucunda ham mukavemetli WC-% 9Co parçalarda yüzey alanı/hacim (Ay/V) oranı arttıkça ağırlık kaybının da arttığı, kalınlık ve hacmin artması ağırlık kaybını azalttığı tespit edilmiştir. Etanol ortamında ve 60°C sıcaklıkta bağlayıcı ayrıştırma işlemi gerçekleştirilen numunelerde optimum sürenin 60 saat olduğu belirlenmiştir.

Anahtar Kelimeler:

TOZ ENJEKSİYON KALIPLAMA, BAĞLAYICI AYRIŞTIRMA, BAĞLAYICI AYRIŞTIRMA SÜRESİ, YÜZEY ALANI/HACİM ORANI

The investigation of the effects of debinding time and dimensions of sample on parts produced from tungsten carbide by powder injection molding

Powder injection molding (PIM) is a method that is emerged from the combination of conventional powder metallurgy technique and plastic injection molding. This method, comprises four basic steps including of preparation of the feedstock, injecting into the mold,the binder removal process and sintering. The binder removal process in PIM effects the ultimate strength achieved in part after sintering. Also if the debinding time is selected as higher than optimum level, production cost will increase, obviously. Therefore, determination of loss of mass that occurs during binder removal process is significant. In this study, tungsten carbide (WC) samples with three different diameters (4,3; 9,75 ve 12 mm) and three different lengths (15, 14, ve 11 mm) were produced by PIM method. Then these samples were subjected to chemical debinding process at four different time, 24, 48, 60 and 72 hours, respectively. Ethanol was used as solvent in the chemical binder removal process, As a result of experiments, the effects of sample thickness, volume, surface area/volume ratio (Ay / V) and debinding time on weight loss were specified by using PIM. According to the this study, as the surface area/volume ratio (Ay / V) is increased the weight loss will increased, while the thickness and volume are increased, weight loss will decreased for the green part of the feedstock. 60 hours is determined as optimum binder removal parameters for the case of 60°C in ethanol.

Keywords:

Powder Injection Molding, Debinding, Debinding time, surface area/volume ratio,

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