Pengaruh Penambahan dan Ukuran Partikel Calcium Hexaaluminate (CA₆) terhadap Sifat Fisik dan Mekanik Refraktori Alumina Rendah

Sulistyawan, Anggoro Harry (2026) Pengaruh Penambahan dan Ukuran Partikel Calcium Hexaaluminate (CA₆) terhadap Sifat Fisik dan Mekanik Refraktori Alumina Rendah. Masters thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Refraktori berbasis alumina rendah telah banyak diterapkan pada berbagai proses industri suhu tinggi. Meskipun demikian, peningkatan sifat mekanik serta ketahanan terhadap thermal shock masih sangat dibutuhkan agar material ini mampu bertahan pada kondisi operasi yang fluktuatif akibat siklus pemanasan-pendinginan mendadak. Penelitian ini mengkaji pengaruh penambahan CA₆ dengan variasi jumlah (0–6%wt) dan ukuran partikel (<45 µm hingga 425–600 µm) terhadap komposisi fasa, densitas, thermal conductivity, kekuatan tekan (CCS), kekuatan lentur (MOR), serta ketahanan thermal shock pada refractori alumina rendah. Karakterisasi dilakukan melalui pengujian difraksi sinar-X (XRD) dan Scanning Electron Microscopy (SEM). Hasil penelitian menunjukkan bahwa penambahan CA₆ ukuran halus (<45 µm) meningkatkan densitas dari 2,26 menjadi 2,30 g/cm³, CCS dari 38,8 menjadi 43,7 MPa, MOR dari 10,1 menjadi 12,5 MPa, serta thermal conductivity dari 1,98 menjadi 2,14 W/m·K. Perubahan ini dipengaruhi oleh peningkatan kandungan corundum dan mekanisme liquid-phase sintering selama proses pemanasan, meskipun disertai penurunan ketahanan thermal shock, yang terbaca dari strength loss ratio dari 23,8% menjadi 29,5%. Pada penambahan 6%wt CA₆ dengan ukuran partikel yang lebih besar, densitas menurun, namun CCS dan MOR meningkat hingga 46,3 MPa dan 16,4 MPa, serta thermal conductivity melonjak hingga 3,01 W/m·K, dan strength loss ratio memburuk hingga 47,8%. Penelitian ini menyimpulkan bahwa CA₆ ukuran kasar mampu meningkatkan sifat mekanik awal (CCS dan MOR) tetapi pada saat yang sama menurunkan kemampuan insulasi termal dan memperburuk stabilitas terhadap thermal shock. Oleh karena itu CA₆ tidak direkomendasikan sebagai penguat refraktori alumina rendah.
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Low-alumina refractories are widely used in high-temperature industrial processes; however, improvements in mechanical properties and thermal shock resistance are still needed to withstand fluctuating operating conditions due to rapid heating-cooling cycles. This study investigates the effect of CA₆ addition with variations in content (0–6%wt) and particle size (<45 µm to 425–600 µm) on phase composition, density, thermal conductivity, cold crushing strength (CCS), modulus of rupture (MOR), and thermal shock resistance of low-alumina refractories. Phase composition and microstructure were examined using X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM). The addition of fine CA₆ (<45 µm) increased density from 2.26 to 2.30 g/cm³, CCS from 38.8 to 43.7 MPa, MOR from 10.1 to 12.5 MPa, and thermal conductivity moderately from 1.98 to 2.14 W/m·K. These changes were influenced by increased corundum formation and liquid-phase sintering during the heating process, although accompanied by a decrease in thermal shock resistance, as indicated by the strength loss ratio increasing from from 23.8% to 29.5%. At a fixed 6%wt CA₆ addition with larger particle sizes, density decreased, but CCS and MOR increased significantly (up to 46.3 MPa and 16.4 MPa, respectively), while thermal conductivity rose sharply to 3.01 W/m·K and strength loss ratio to 47.8%. This study concludes that coarse CA₆ improves initial mechanical properties (CCS and MOR), while simultaneously decreasing thermal insulation stability and deteriorating thermal shock stability. Therefore, CA₆ is not suitable as a reinforcement for low-alumina refractories.

Item Type:	Thesis (Masters)
Uncontrolled Keywords:	calcium hexaaluminate-CA₆, refraktori alumina rendah, ukuran partikel, sifat mekanik, ketahanan thermal shock, low-alumina refractory, calcium hexaaluminate, CA₆, particle size, mechanical properties, thermal-shock resistance
Subjects:	H Social Sciences > HD Industries. Land use. Labor > HD9590+ Ceramic Q Science T Technology > TP Chemical technology > TP155.7 Chemical processes.
Divisions:	Faculty of Industrial Technology and Systems Engineering (INDSYS) > Material & Metallurgical Engineering > 27101-(S2) Master Thesis
Depositing User:	Anggoro Harry Sulistyawan
Date Deposited:	15 Jul 2026 08:55
Last Modified:	15 Jul 2026 08:55
URI:	http://repository.its.ac.id/id/eprint/135024

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