Sains Malaysiana 41(8)(2012): 1005–1009

Densification and Mechanical Properties of Electroconductive Si3N4 -Based

Composites Prepared by Spark Plasma Sintering

(Penumpatan dan Sifat-Sifat Mekanik Komposit Berasaskan Si3N4 disediakan

Melalui Pensinteran Percikan Plasma)

Norhayati Ahmad*

Department of Materials Engineering, Faculty of Mechanical Engineering

Universiti Teknologi Malaysia, 81310 UTM Skudai, Johor, Malaysia

Hidekazu Sueyoshi

Department of Nano-structure and Advanced Materials, Graduate School of Science and Engineering

Kagoshima University, 1-21-40 Korimoto, Kagoshima 890-0065 Japan

Diserahkan: 25 Januari 2010 / Diterima: 25 Mac 2011

ABSTRACT

Si3N4-TiN composites were prepared by conventional powder processing (SPS1) and in-situ reaction sintering (SPS2). Rapid densification of SPS was achieved for sample SPS1 and SPS2 within a few minutes at low temperature. Sample SPS1 sintered at 1550ºC showed rapid transformation of α to β Si3N4 while for sample SPS2 sintered at 1350ºC, a significant degree of α to β Si3N4 transformation was achieved. Homogeneous distribution of equiaxed TiN grains in matrix Si3N4 resulting in high hardness (21.7 GPa) and bending strength (621 MPa) for sample SPS1 sintered at 1550ºC. Elongated TiN grains as the reinforcement of Si3N4 matrix composites was found to increase the toughness (8.39 MPa m1/2) of sample SPS2 sintered at 1350ºC. The composites prepared by SPS2 sintered at 1250-1350ºC had low electrical resistivity and could be machined by electrical discharge machining (EDM).

Keywords: Densification; mechanical properties; silicon nitride-titanium nitride composites; spark plasma sintering

ABSTRAK

Komposit Si3N4-TiN dihasilkan dengan kaedah pemprosesan serbuk yang lazim (SPS1) dan pensinteran tindak balas in-situ (SPS2). Pemandatan yang tinggi diperoleh daripada sampel SPS1 dan SPS2 selama beberapa minit pada suhu yang rendah. Sampel SPS1 yang disinter pada suhu 1550ºC menunjukkan transformasi daripada α ke β Si3N4 yang pantas, manakala sampel SPS2 yang disinter pada suhu 1350ºC menunjukkan transformasi α ke β Si3N4 ke tahap yang signifikan. Taburan butiran TiN yang berbentuk sepaksi secara seragam dalam matrik Si3N4 memberikan kekerasan (21.7 GPa) dan kekuatan lenturan (621 MPa) yang tinggi bagi sampel SPS1 yang disinter pada suhu 1550ºC. Butiran TiN yang berbentuk panjang sebagai penguat dalam matrik komposit Si3N4 boleh meningkatkan keliatan (8.39 MPa m1/2) bagi sampel SPS2 yang disinter pada suhu 1350ºC. Sampel SPS2 yang disinter pada suhu 1250-1350ºC mempunyai rintangan elektrik yang rendah dan boleh dimesin dengan pemesinan nyahcas elektrik (EDM).

Kata kunci: Komposit silikon nitrat-titanium nitrat; pensinteran percikan plasma (SPS); penumpatan; sifat mekanikal

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*Pengarang surat-menyurat;  email: nhayati@fkm.utm.my