Material preparation

Commercially available soda-lime glass powder with an average particle size of 14 μm (B200, Nissho-materials Co., Ltd., Mie, Japan) was used as the matrix, and an 80% Ni-20% Cr alloy with a size range of 20–53 μm (1616-02, Höganäs Belgium SA, Ath, Belgium) was used as the metallic alloy powder.

The effect of the relative volume of Ni-Cr alloy particles on the electrical and mechanical properties of soda-lime glass/Ni-Cr alloy particle composites was studied in composites containing 20, 30, 40, 50, 60, 70, and 80 vol% particles. Ni-Cr alloy particles were milled using a wet planetary ball mill (Pulverisette-6, Fritsch GmbH, Idar-Oberstein, Germany) with Si₃N₄ balls in ethanol for 10 h to obtain disk-like particles and a homogeneous mixture of soda-lime glass powder and Ni-Cr alloy powder. The slurry was dried in a rotary evaporator to remove the ethanol. The mixture was sintered by SPS (Plasman CSP-KIT-0212, S.S. Alloy Co., Ltd., Hiroshima, Japan) at 973 K under 38 MPa and pressed in a carbon die to fabricate ϕ10 × 1.5 mm composites to evaluate the bulk resistivity. To measure the three-point flexural strength and fracture toughness, composites with dimensions of 70 × 70 × 5 mm were fabricated by SPS (SPS3.20MK-IV, Sumitomo Coal Mining Co., Ltd., Tokyo, Japan) at 973 K under 38 MPa in a vacuum.