Sains Malaysiana 41(1)(2012): 121–127

Kesan Rawatan Haba Terhadap Mikrostruktur Katod Berliang Ag₂O₃-Bi₂O₃ di atas Substrat Keluli Kalis Karat yang disediakan dengan Kaedah Pengecatan Sluri

(Effect of Heat Treatment on the Microstructure of Porous Ag₂O₃-Bi₂O₃ Cathode on Stainless

Steel Substrates Prepared by the Slurry Painting Method)

Dedikarni Panuh, Andanastuti Muchtar*, Norhamidi Muhamad & Wan Ramli Wan Daud

Institut Sel Fuel, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor D.E.

Malaysia

Received: 21 April 2011 / Accepted: 7 June 2011

ABSTRACT

The influence of thermal treatment on the microstructure of Ag2O3-Bi2O3 porous cathode on stainless steel substrates has been investigated. The composite cathode material has been successfully deposited on the substrates by the slurry painting method. The cathode was later thermally treated at different temperatures of 400, 500, 600, 700, 800 and 830^oC for 1 h in the atmosphere. Thermal analysis of the dried slurry was conducted in order to determine the heating schedule for eliminating the organic components using thermogravimetry analysis (TGA) and differential scanning calorimetry (DSC). The TGA and DSC analyses confirmed that the organic component was fully decomposed below 418^oC, whereas the formation of the composite cathode oxide phases took place at temperatures beyond 600^oC. The microstructure of the thermally treated cathode was determined using scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. The SEM results showed that the grain size of the cathode increased with increase in temperature during thermal treatment. The X-ray diffraction (XRD) analyses confirmed the presence of δ-Bi2O3 phase on the cathode. The Ag2O3-Bi2O3 cathode deposited on the stainless steel substrates was found to have a porosity of 53%, 51%, 39% and 28% after 1, 2, 3, and 4 coatings, respectively, and upon thermal treatment at 800°C for 1 h.

Keywords: Bismuth oxide; porous cathode; slurry painting method

ABSTRAK

Pengaruh rawatan haba terhadap mikrostruktur katod berliang Ag2O3-Bi2O3 di atas substrat keluli kalis karat telah dikaji. Komposit katod telah diendapkan ke atas substrat dengan menggunakan kaedah pengecatan sluri. Katod yang terhasil dirawat haba pada suhu 400, 500, 600, 700, 800 dan 830oC selama 1 jam dalam tekanan atmosfera. Analisis terma terhadap sluri kering telah dikaji untuk mendapatkan jadual pemanasan bagi penyingkiran komponen organik dengan menggunakan analisis termogravimetri (TGA) dan kalori imbasan kebezaan (DSC). Analisis TGA dan DSC mendapati penyingkiran komponen organik terjadi pada suhu di bawah 418oC dan fasa oksida komposit katod terbentuk pada suhu melebihi 600oC. Mikrostruktur katod terawat haba ditentukan dengan menggunakan mikroskop elektron imbasan (SEM) dan belauan sinar-X (XRD). Keputusan SEM menunjukkan yang saiz ira bagi katod meningkat dengan peningkatan suhu rawatan haba. Analisis pembelauan sinar-X mengesahkan kehadiran fasa δ-Bi2O3 di atas katod. Katod Ag2O3-Bi2O3 yang diendapkan di atas substrat keluli kalis karat dengan proses pengulangan salutan 1, 2, 3, dan 4 kali didapati masing-masing mempunyai keliangan 53%, 51%, 39% dan 28% setelah melalui proses rawatan haba pada suhu 800oC selama 1 jam.

Kata kunci: Bismut oksida; kaedah pengecatan sluri; katod berliang

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*Corresponding author; email: muchtar@eng.ukm.my