Mekanik Alaşımlama Yöntemiyle Volfram Esaslı Toz Malzemelerinin Sentezlenmesi Ve Sinterleme Davranışları

Abstract

ÖZET Sunulan Yüksek Lisans tez çalısmasında elementel volfram ve karbon tozlarının Spex cihazında değişik sürelerde Mekanik Alaşımlanarak ( MA) katı hal reaksiyonları ile volfram karbür sentezlenmiştir. Bu işlemi takiben değişen sürelerde Mekanik Alaşımlama yapılarak toz boyut dağılımı ölçülmüştür. Ayrıca oluşan fazların incelenmesi için X-ışınları analizi yapılmıştır. Değişen alaşımlama sürelerinde tozların Taramalı Elektron Mikroskobu(SEM) ile mikroyapısı incelenmiştir. Tozların değişen MA sürelerde ki yüzey alan değişimi, analiz edilerek toz boyut değişimi incelenmeye çalışılmıştır. İkinci aşamada MA yapılmış volfram karbür tozları mekanik pres ile şekillendirilerek belli sıcaklıkta koruyucu gaz ortamında (Argon, Azot) sinterlenmiştir. Daha sonra Taramalı Elektron Mikroskobu ile mikroyapıları incelenmiştir. Aynı işlemler volfram karbür tozuna nikel toz bağlayıcı ilave edilerek gerçekleştirilmiştir.

SUMMARY The use of Powder metallurgy to form intricately shaped parts by pressing and sintering was introduced in the 19th century. The first commercial application of Powder Metallurgy occured when carbon and later osmium, zirconium, vanadium, tantalium and tungsten, was used for incandescent lamp filaments. Tungsten was soon recognized as the best material for lamp filaments. It was known that tungsten granules combined readily with carbon at high temperatures to yield an extremely hard compound so that this material was used as the basis for a very hard, durable tool material known as cemented carbides. Cemented carbides are products of the Powder metallurgy process; they consist of primarily of minute particles of tungsten and carbon powders to synthesize WC via solid state reactions at room temperatures was carried out with Spex 8000 and then, the effect of milling time investigated on WC production, for instance; in this study MA was made; 5, 10, 15, 35 hours and its particle size was calculated by using Laser Particle Size Analyiser, bet analyies, XRD and SEM studies after alloying. Firstly, pure W and pure Graphite were mixed without binder than pressed by using uniaxial mechanic pres after MA alloying. Following this step MA powders was sintered by using inert atmosphere at 1410C° without adding any metallic binder. Sintered compacts were analyised by X-rays, SEM and EDS Secondly, W and Graphite(which was made MA) and added metallic binder(Ni), which were mixed by using planatory ball mill. İt’s 90% percent composition is WC and other is Ni and then pressed by using uniaxial press and sintered the same conditions. After these sintered compacts which were analsied by X-rays, SEM and EDS . Finally this two steps are compare according to, change density, volume and weight, moreover; aim of this study, investigated effect of Ni element on WC microstructure.