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All Journal Telaah Science and Technology Indonesia Teknologi Indonesia Metalurgi Metalurgi

Toto Sudiro

Lembaga Ilmu Pengetahuan Indonesia (LIPI)

Author-ID : 388209

Biochemistry, Genetics & Molecular Biology Chemical Engineering, Chemistry & Bioengineering Computer Science & IT Energy Environmental Science Industrial & Manufacturing Engineering Materials Science & Nanotechnology Physics

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PREPARASI MAGNET SINTER Pr-Fe-B DENGAN MENGGUNAKAN SPARK PLASMA SINTERING Sudiro, Toto; Sardjono, Priyo; Thosin, Kemas Ahmad Zaini; Muljadi, Muljadi
Telaah Vol 32, No 1 (2014)
Publisher : Research Center for Physics

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14203/tel.32.1.177

Penelitian ini bertujuan untuk mempreparasi sinter Pr-Fe-B dengan teknik spark plasma sintering (SPS). Proses fabrikasi dilakukan di dalam ruang vakum bertekanan kurang dari 60 Pa di mana powder dikompaksi padatekanan 40 MPa pada temperatur yang berbeda: 800 oC, 900 oC, dan 1050 oC. Komposisi fase dari kompak material tersebut dianalisis dengan X-ray diffractometer (XRD Shimadzu-7000TM;). Sampel kemudian dimagnetisasi dengan impulse magnetizer K-series, Magnet-Physik Dr. Steingroever GmbHTM. Hasil penelitian menunjukkan bahwa dengan meningkatnya temperatur SPS, kuat medan magnet permukaannya menurun. Hal ini diduga disebabkan oleh pembentukan Fe phase yang memiliki sifat buruk terhadap properti magnet Pr-Fe-B.

STRUCTURE AND HARDNESS CHARACTERISTICS OF 50Cr-50Al COATING PREPARED BY A MECHANICAL ALLOYING TECHNIQUE: EFFECTS OF HEAT TREATMENT TEMPERATURE Sudiro, Toto; Sebayang, Perdamean
Teknologi Indonesia Vol 38, No 3 (2015)
Publisher : LIPI Press

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14203/jti.v38i3.247

In the present work, a mechanical alloying technique was used to prepare 50Cr-50Al (in atomic, at %) coating on the surface of low carbon steel. The coated samples were then annealed in a vacuum at elevated temperatures of 600, 700, 800, and 900C for 2h, separately. The effects of annealing temperature on the structure characteristic of 50Cr-50Al coating were studied by XRD and SEM-EDX, and coating hardness was measured by micro-Vickers hardness test. The results showed that the annealing process led to the formation of inter-metallic phases and interdiffusion of Fe element from the substrate and Cr, Al elements from the coating, depending on annealing temperature. As annealing temperature increased to 900C, however, X-ray diffraction analysis indicated the formation of Al2O3. Meanwhile, the hardness of cross-sectional of coating increased after annealing at 600C. The coating hardness decreased as annealing temperatures increased.

THE EFFECT OF ZnO ADDITIVE ON PHYSICAL PROPERTIES AND MICROSTRUCTURE OF BaFe12O19 MAGNETIC MATERIAL Sebayang, Perdamean; Sudiro, Toto; Aryanto, Didik; Nugraha, Endra
Teknologi Indonesia Vol 39, No 2 (2016)
Publisher : LIPI Press

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14203/jti.v39i2.265

Preparation of BaFe 12 O 19 powder containing varying amount of ZnO as 5, 10, 15 and 20 % by mass were prepared by a high energy milling (HEM) for 1 hour and compacted into a pellet using 80 kgf/cm 2 in compressive pressure. The samples were sintered at elevated temperatures of 800 and 1,000 o C for 2 hours, separately. The characterization results indicated that BaFe 12 O 19 -10 mass % ZnO exhibits excellent in physical and magnetic properties that can be potentially used for recording media and microwave absorbing material applications.

Karakterisasi Struktur Coating Fe-25Al Yang Difabrikasi Dengan Metode Paduan Mekanik [Structure Characterization of Fe-25Al Coating Fabricated by Mechanical Alloying Method] Nisa, Khoirun; Aryanto, Didik; Sudiro, Toto; Sebayang, Perdamean; Aji, Mahardika P
Metalurgi Vol 31, No 2 (2016): Metalurgi Vol. 31 No. 2 Agustus 2016
Publisher : Pusat Penelitian Metalurgi dan Material - LIPI

Fe-25Al coating has been prepared on low carbon steel substrate by using a mechanical alloying technique. Structure of Fe-25Al coating before and after heat treatment at 600, 700, and 800 °C was studied by using XRD (x-ray diffraction) characterization. SEM (scanning electron microscopy) and EDX (energy disperse xray) were used to identified the morphology of cross-section of Fe-25Al coating after mechanical alloying process. The result of SEM, EDX and XRD showed that the Fe-25Al deposited uniformly on low carbon steel. The Fe-25Al coating formation has a solid solution Fe(Al) phase. Heat treatment caused the changing in the phase of Fe-25Al coating, where the Fe3Al phase with orientation of (110), (200) and (211) plane was formed. The optimum of diffusion process was occurs at temperature of 600C which was indicated by the increasing in the crystalline size and followed by the decreasing in the dislocation density and lattice strain. Increasing temperature on the heat treatment caused the changing in the structure parameter, such as lattice parameter, crystalline size, lattice strain and dislocation density. In this work, heat treatment on the Fe-25Al coating influenced the changing in crystal defect such as grain boundaries, vacancy and dislocation. It affected thechanges of lattice strain and crystalline size of Fe-25Al coating.AbstrakCoating Fe-25Al telah dipreparasi di atas substrat baja karbon rendah dengan menggunakan metode paduan mekanik. Struktur dari coating Fe-25Al sebelum dan setelah diberi perlakuan panas pada 600°C, 700°C, and 800°C dipelajari dengan menggunakan karakterisasi X-ray diffraction (XRD). Scanning electron microscopy (SEM) dan energy disperse X-ray (EDX) digunakan untuk mengetahui morfologi dari penampang lintang coating Fe-25Al setelah proses paduan mekanik. Hasil dari SEM, EDX dan XRD menunjukkan bahwa Fe-25Al telah terdeposisi seragam pada substrat baja karbon rendah. Coating Fe-25Al yang terbentuk memiliki fasa solid solution Fe(Al). Perlakuan panas menyebabkan perubahan fasa pada coating Fe-25Al, dimana terbentuk fasa Fe3Al dengan orientasi bidang (110), (200) dan (211). Proses difusi optimum terjadi pada suhu 600°C yang ditunjukkan dengan peningkatan ukuran butir, diikuti dengan berkurangnya densitas dislokasi dan regangan kisi. Meningkatnya suhu pada perlakuan panas menyebabkan perubahan parameter struktur seperti parameter kisi, ukuran kristal, regangan kisi dan kerapatan dislokasi. Dalam pekerjaan ini, perlakuan panas pada coating Fe-25Al mempengaruhi perubahan cacat kristal seperti batas butir, kekosongan dan dislokasi. Hal tersebut berakibat pada perubahan regangan kisi dan ukuran kristal dari coating Fe-25Al.

Perlakuan Panas Ganda pada Fabrikasi Film Tipis AZO Nanokristal dengan Teknik Spray : Studi XRD [Double Heat Treatments On The Fabrication Of Nanocrystalline Azo Thin Films By Spray Technique: XRD Studies] Aryanto, Didik; Husniya, Naimatul; Sudiro, Toto; Hastuti, Ema
Metalurgi Vol 32, No 2 (2017): Metalurgi Vol. 32 No. 2 Agustus 2017
Publisher : Pusat Penelitian Metalurgi dan Material - LIPI

XRD characterization was used to study the effect of single and double thermal treatment on the fabrication of nanocrystalline Al-doped ZnO (AZO) thin films deposited by spray technique. In the single thermal treatment, nanocrystalline AZO thin film with a wurtzite hexagonal polycrystalline structure was formed at temperatures of 500 °C and 600 °C. An increasing of treatment temperature led to the increase of crystalline size and the decrease of dislocation density. The double thermal treatment on nanocrystalline AZO thin films resulted in a small change in diffraction pattern. This indicated that the crystal parameters of nanocrystalline AZO thin films changed after receiving a second thermal treatment. Nanocrystalline AZO thin films which was thermal treatment at temperatures of 500 °C in air environment and continued at temperatures of 600 °C in vacuum showed that the decrease of average crystal size and the presence of crystal defect (an increase of strain and dislocation). Different results were shown in the nanocrystalline AZO thin film after thermal treatment attemperatures of 600 °C in air environment then followed by vacuum condition. The crystal quality of nanocrystalline AZO thin films was improved, which was indicated by an increase of the average crystal size and reduce of the strain value and dislocation density. Based on the obtainedresults, the double heat treatment effected the crystal parameter and the quality of nanocrystalline AZO thin films deposited by spray technique.AbstrakKarakterisasi XRD telah digunakan untuk mempelajari efek perlakuan panas tunggal dan ganda pada fabrikasi film tipis ZnO doping Al (AZO) nanokristal yang dideposisikan dengan teknik spray. Pada perlakuan panas tunggal, film tipis AZO nanokristal dengan struktur polikristal heksagonal wurtzite terbentuk pada suhu 500 °C dan 600 °C. Peningkatan suhu menyebabkan peningkatan ukuran kristal dan pengurangan kerapatan dislokasi. Perlakuan panas ganda pada film tipis AZO nanokristal mengakibatkan perubahan kecil pola difraksi. Hal ini mengindikasikan bahwa parameter kristal film tipis AZO nanokristal berubah setelah mendapat perlakuan panas kedua. Film tipis AZO nanokristal yang diberikan perlakuan panas pada suhu 500 °C dalam lingkungan udara dan dilanjutkan hingga suhu 600 °C dalam kondisi vakum memperlihatkan bahwa rata-rata ukuran kristal berkurang dan muncul cacat kristal (regangan dan kerapatan dislokasi meningkat). Hasil yang berbeda ditunjukkan pada film tipis AZO nanokristal yang diberikan perlakuan panas pada suhu 600 °C dalam lingkungan udara kemudian dilanjutkan dengan suasana vakum. Kualitas kristal film tipis AZO nanokristal meningkat, yang diindikasikan dengan peningkatan rata-rata ukuran kristal, berkurangnya nilai regangan dan kerapatan dislokasi. Berdasarkan pada hasil yang didapat, perlakuan panas ganda berpengaruh pada parameter dan kualitas kristal film tipis AZO nanokristal yang dideposisikan dengan teknik spray.

DEPOSISI LAPISAN Fe-Si-Al-Mg PADA CARBON STEEL DENGAN TEKNIK PEMADUAN MEKANIK Lusita, Lusita; Fahdiran, Riser; Sudiro, Toto; Hermanto, Bambang
Metalurgi Vol 34, No 1 (2019): Metalurgi Vol. 34 No. 1 April 2019
Publisher : Pusat Penelitian Metalurgi dan Material - LIPI

Lapisan Fe-Si-Al-Mg dengan variasi berat ferrosilicon, Mg dan Al yaitu 50(Fe-Si)-37.5Al-12.5Mg, 50(Fe-Si)-25Al-25Mg, dan 50(Fe-Si)-12.5Al-37.5Mg telah dipreparasi pada substrat baja karbon rendah dengan menggunakan teknik pemaduan mekanik (mechanical alloying). Struktur dari lapisan Fe-Si-Al-Mg dipelajari menggunakan XRD (X-ray Diffraction) untuk mengetahui fasa yang terbentuk dan OM (Optical Microscope) untuk mengetahui ketebalan lapisan yang didapatkan. Hasil X-ray Diffraction dan Optical Microscope menunjukkan bahwa lapisan Fe-Si-Al-Mg telah berhasil dideposisikan pada substrat baja karbon rendah. Lapisan Fe-Si-Al-Mg yang terbentuk memiliki fasa intermetalik FeSi2, Mg2Si dan Al0.7Fe3Si0.47. Setiap komposisi menunjukkan ketebalan lapisan yang berbeda. Ketebalan lapisan cenderung menurun dengan meningkatnya konsentrasi magnesium dan berkurangnya konsentrasi aluminium.Kata Kunci: lapisan, Fe-Si-Al-Mg, pemaduan mekanik, fasa, ketebalan.

STRUCTURE, MECHANICAL PROPERTIES, AND OXIDATION RESISTANCE OF MN-RICH FE-MN-AL ALLOYS Desiati, Resetiana Dwi; Sutiawan, Edi; Sudiro, Toto; Hermanto, Bambang
Metalurgi Vol 37, No 3 (2022): Metalurgi Vol. 37 No. 3 Desember 2022
Publisher : National Research and Innovation Agency (BRIN)

In this study, Mn-rich Fe-Mn-Al alloys with different Al content (Al = 0, 3, and 5 % by weight) were fabricated from ferromanganese lumps using a conventional powder metallurgy technique. The samples were compacted in 1 cm steel dies using a load of 8 tons and then sintered at 1100 °C for 2 h in a tubular furnace under a vacuum condition of around 0.5 mbar. To evaluate the effect of Al addition to Fe-Mn-Al alloy, the Archimedes principle and Vickers hardness were applied to estimate the density and hardness of the compact alloys. Moreover, the high-temperature oxidation resistance of the alloy was evaluated at 800 °C for 8 cycles. The structure of the alloy before and after oxidation was studied by means of X-Ray Diffractometer and SEM-EDS. The XRD analysis results show that the FeMn-0Al alloy is mainly composed Fe3Mn7 phase, the presence of FeAl phase at 3 wt% Al, and Al8Mn5 phase at 5 wt% Al. The density and hardness of Fe-Mn-Al alloys decreased with the increased Al content. Fe-Mn-Al alloy without Al addition exhibits poor oxidation resistance since the first cycle of the test. The results of microstructural analysis showed that although the alloy with the addition of 3 wt% Al showed less mass gain after being exposed for 8 cycles at 800 °C, the Fe-Mn-Al alloy with 5 wt% tended to be more resistant to oxidation and had no cracking defects. The structure of the oxide formed on the surface of the alloy is composed of two layers (ie; outer and inner layer) which are affected by each alloy composition.

Significant Reduction in Lattice Thermal Conductivity of (PbTe)0.95 - (PbS)0.05 Thermoelectric Materials Through Liquid Silicon Quenching Ginting, Dianta; Nurlela, Ai; Nanto, Dwi; Mashadi; Sudiro, Toto; Kristiantoro, Tony; Rhye, Jong-Soo
Science and Technology Indonesia Vol. 10 No. 4 (2025): October
Publisher : Research Center of Inorganic Materials and Coordination Complexes, FMIPA Universitas Sriwijaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.26554/sti.2025.10.4.1087-1095

Thermoelectric materials are game-changers, that have the ability to transform waste heat into electrical energy, making them a potential renewable energy solution to reduce reliance on fossil fuels. The standard metric for evaluating thermoelectric materials is the dimensionless figure of merit, ZT, which is markedly influenced by lattice thermal conductivity (ĸl ). Higher thermal transport through the lattice lowers the ZT value, reducing the material’s efficiency. Therefore, finding ways to decrease ????l is critical for boosting thermoelectric performance. In our research, we explored an innovative approach by applying a quenching technique using liquid silicon to reduce thermal conductivity (ĸT ) due to lattice vibrations. We compared the lattice conductivity (ĸl ) of materials with and without this liquid silicon quenching process. The results were striking: at 300 K, quenching lowers the lattice thermal conductivity by about 40.1 %, and at 800 K, it is still reduced by roughly 24.7%compared with pristine PbTe. Even more impressive, when compared to non-quenched (PbTe)0.95 − (PbS)0.05 alloys, at 300 K, the silicon-quenched sample attains an additional ĸl reduction of roughly 16.1 %, while at 800 K the extra decrease is about 13.0%. These findings highlight that liquid silicon quenching is a highly effective method for lowering ĸl of PbTe thermoelectric materials. This approach paves the way for developing next-generation thermoelectric materials that are more efficient, particularly for eco-friendly waste heat recovery applications. Our work opens new possibilities for sustainable energy innovation.

Co-Authors Aji, Mahardika P Bambang Hermanto Didik Aryanto Dwi Nanto, Dwi Ginting, Dianta Hastuti, Ema Husniya, Naimatul Kemas Ahmad Zaini Thosin Khoirun Nisa Lusita Lusita Mashadi Muljadi Muljadi Nugraha, Endra Nurlela, Ai Perdamean Sebayang Priyo Sardjono Resetiana Dwi Desiati, Resetiana Dwi Rhye, Jong-Soo Riser Fahdiran Sutiawan, Edi Tony Kristiantoro, Tony

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