Synthesis and characterization of Tungsten Carbide
Master thesis
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http://hdl.handle.net/11250/2615694Utgivelsesdato
2016Metadata
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Sammendrag
From the very early stage of human civilization tungsten carbide is used as the hard metal in geoengineering for producing drill buttons and other wear resistance parts. However due to its limited storage in earth as well as expensive cost recent research work are going on to replace tungsten based hard metals with ceramic based nanocomposites. Considering the scope of research, in this study tungsten carbide supported silicon carbide (α-SiC & β-SiC) and calcium aluminate were synthesized and later wetted by low-temperature metal alloy in order to form ceramic based metal matrix composite. All supports were coated using incipient wetness impregnation (Pechini Method) and two different types of the precursor. The loaded sample was then calcined at different temperature (500°C for SiC and 900°C for calcium aluminate) using air flow for three hours. After calcination, carburization was carried out using both external carburizing agents and direct method. Following that wetting and infiltration experiment was carried out using carbide coated sample and low-temperature metal alloy at high temperature for a different holding time. All samples were characterized by different characterization techniques (SEM, XRD, and BET) after every experimental stage. Analysis of XRD results showed the presence of tungsten carbide phase for both SiC and calcium aluminate support after carburization. From both SEM and EDX analysis, it was found that complete coating of tungsten carbide can be achieved for alpha silicon carbide support (α-SiC) using ammonium hydroxide and ammonium metatungstate (AMT) precursor. However, complete coating of tungsten carbide was confirmed for calcium aluminate support without the use of ammonium hydroxide solution. Successful wetting of metal was observed for all types of coated supports. However, successful infiltration of metal alloy inside the coated sample matrix was only observed for β-SiC and calcium aluminate support.