Claim Missing Document
Check
Articles

Found 19 Documents
Search

PENINGKATAN REDUKSI CAMPURAN PASIR BESI-GRAFIT DENGAN MECHANICAL ALLOYING Alfian Noviyanto; Agus Sukarto Wismogroho; Wisnu Ari Adi; Iwan Setiawan; Nurul Taufiqu Rochman
Jurnal Sains Materi Indonesia Vol 8, No 3: JUNI 2007
Publisher : Center for Science & Technology of Advanced Materials - National Nuclear Energy Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (1579.428 KB) | DOI: 10.17146/jsmi.2007.8.3.4700

Abstract

PENINGKATAN REDUKSI CAMPURAN PASIR BESI-GRAFIT DENGAN MECHANICAL ALLOYING. Untuk meningkatkan reduksi pasir besi, telah dilakukan mechanical alloying pada campuran pasir besi-grafit dengan komposisi 10 at% dan 15 at%. Sampel di-milling menggunakan high energy ball mill PBM4A selama 100 jam dalam suasana argon, kemudian dibakar pada suhu 1400 oC dengan interval waktu tertentu untuk melihat terjadinya metalisasi. Analisis karakterisasi dilakukan dengan menggunakan X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM) dan Energy Disperse Spectroscopy (EDS). Setelah dimilling terlihat ukuran partikel pasir besi semakin kecil dan masuknya partikel grafit ke dalam pasir besi, sehingga reduksi langsung mungkin terjadi karena area kontak yang besar antara pasir besi-grafit. Hasil metalisasi dibandingkan dengan sampel pasir besi yang dibuat dengan pencampuran biasa. Hasil menunjukkan metalisasi hanya terjadi pada pasir besi dengan ball mill, sedangkan pasir besi yang dicampur biasa tidak terjadi metalisasi sama sekali.
Sintesis kalsium pirofospat (Ca2P2O7) dari limbah cangkang telur dengan metode solvothermal Ihsanul Huda; Retno Kusumaningrum; Mi'raj Shabrin Jamil; Wahyu Bambang Widayatno; Agus Sukarto Wismogroho; Nurul Taufiqu Rochman; Alfian Noviyanto
CHEMPUBLISH JOURNAL Vol. 5 No. 1 (2020): Chempublish Journal
Publisher : Universitas Jambi, Fakultas Sains dan Teknologi, Program Studi Kimia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22437/chp.v5i1.8669

Abstract

Kalsium pirofospat telah berhasil disintesis dengan menggunakan metode solvothermal. Bahan dasar yang digunakan adalah limbah cangkang telur ayam dan bebek. Cangkang telur ayam dan bebek dibersihkan dan digerus, kemudian dikalsinasi pada temperatur 1000°C selama 2 jam untuk mendapatkan serbuk CaO. Serbuk CaO kemudian dicampurkan dengan H3PO4 dan dimasukkan ke dalam bejana solvothermal. Proses solvothermal dilakukan pada temperatur 130°C selama 16 jam. Fasa tunggal CaHPO4 diperoleh setelah proses solvothermal. Kalsinasi serbuk CaHPO4 dilakukan pada tungku muffle dengan temperatur 800°C selama 2 jam dan kondisi atmosfir biasa. Hasil analisa fasa menunjukkan terbentuknya fasa tunggal kalsium pirofospat (Ca2P2O7) tanpa adanya fasa pengotor lainnya. Hasil ini menunjukkan perbandingan Ca dan P adalah 1. Mikrostruktur kalsium pirofospat yang terbentuk agak kasar dengan ukuran partikel rata-rata 590 ± 43 nm untuk cangkang telur ayam dan 455 ± 32 nm untuk cangkang telur bebek. Studi lebih lanjut diperlukan untuk mendapatkan kondisi optimum dari proses solvothermal limbah cangkang telur sehingga bisa didapatkan kalsium pirofospat yang mempunyai ukuran lebih halus dan seragam.
THE EFFECT OF POLYSILAZANE ON THE DENSIFICATION AND MECHANICAL PROPERTIES OF SICF/SIC COMPOSITES Alfian Noviyanto
SINERGI Vol 24, No 1 (2020)
Publisher : Universitas Mercu Buana

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (931.557 KB) | DOI: 10.22441/sinergi.2020.1.002

Abstract

The effect of polysilazane on the densification and mechanical properties of SiCf/SiC composites was examined thoroughly. The polysilazane was infiltrated into the fiber area, followed by pyrolysis at 1450°C for 4 h in an argon atmosphere. Furthermore, the SiC fabrics contain the pyrolyzed polysilazane was infiltrated by β-SiC slurry and sintered at 1750°C for 2 h in an argon atmosphere. The density of SiCf/SiC composites with and without the addition of polysilazane was 2.65 and 3.05 g/cm3, respectively. The pores in the fiber area were observed for the SiCf/SiC composites with the addition of polysilazane. However, the fine-grained size in the matrix area was obtained by the addition of polysilazane. The average grain size of the SiCf/SiC composite with and without the addition of polysilazane was 253 and 740 nm, respectively. Indeed, the hardness of the matrix area for SiCf/SiC composites with the addition of polysilazane (31.6 ± 1.8 GPa) was higher compared to SiCf/SiC composites without polysilazane (27.4 ± 1.6 GPa).
Silicon Carbide/Polysilazane Composite: Effect of Temperature on the Densification, Phase, and Microstructure Evolution Fiqhi Fauzi; Alfian Noviyanto; Pipit Fitriani; Amirudin Wibowo; Toto Sudiro; Didik Aryanto; Nurul Taufiqu Rochman
Indonesian Journal of Chemistry Vol 22, No 2 (2022)
Publisher : Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22146/ijc.69118

Abstract

This paper reports a route to suppress the grain growth in silicon carbide (SiC) during its sintering by combining it with polysilazane (PSZ). SiC was mixed with PSZ in a 1:1 weight ratio and sintered at 1600, 1700, and 1800 °C in a hot-pressing furnace. A satisfactory density was obtained at sintering temperatures > 1600 °C. The grain sizes of the SiC/PSZ composites sintered at 1700 and 1800 °C were 112 and 125 nm, respectively. The grain shape of the SiC/PSZ composite sintered at 1700 °C was circular and mainly similar to the initial shape of the SiC powder. Grain shape accommodation was observed at a sintering temperature of 1800 °C. It is suggested that different sample shapes were affected by different liquid phase formations. Silicon oxynitride (Si2N2O) was formed and played an important role in densification and microstructure generation.
Effect of Applied Pressure During Sintering on the Densification and Mechanical Properties of SiCf/SiC Composites Prepared by Electrophoretic Infiltration Noviyanto, Alfian
Makara Journal of Science Vol. 24, No. 4
Publisher : UI Scholars Hub

Show Abstract | Download Original | Original Source | Check in Google Scholar

Abstract

SiC-fiber-reinforced SiC matrix ceramic (SiCf/SiC) composites were successfully fabricated by electrophoretic infiltration and sintering at various applied pressures. The effect of applied pressure (i.e., 5, 10, and 20 MPa) was thoroughly examined, and applied pressure appears to influence the densification and mechanical properties of SiCf/SiC composites. The densities of SiCf/SiC composites prepared at applied pressure of 5, 10, and 20 MPa were 2.99, 3.10, and 3.16 g/cm3, respectively. All samples showed dense microstructures in their matrix areas; however, many closed pores were found with increasing pressure. Pressure induced densification in the fiber area, and 20 MPa was determined to be the minimum pressure required for adequate densification. The liquid phase in the matrix area was effectively maintained at a high applied pressure, which resulted in densification. However, the liquid phase redistributed to the matrix or near the matrix area at applied pressures of MPa, leading to pores in the fiber areas of these samples. The highest flexural strength of 262 ± 18 MPa for the SiCf/SiC composite was achieved at an applied pressure of 20 MPa. Meanwhile, the flexural strengths of the composites prepared at 5 and 10 MPa were 198 ± 41 and 238 ± 32 MPa, respectively.
Effect of Milling on the Densification of SiC-BasedComposites from Polysilazane Noviyanto, Alfian; Nishimura, Toshiyuki
Makara Journal of Technology Vol. 20, No. 3
Publisher : UI Scholars Hub

Show Abstract | Download Original | Original Source | Check in Google Scholar

Abstract

High density SiC-based composites from polysilazane were fabricated by high energy milling and hot pressing. After cross-linking at 200 °C, the polysilazane was pyrolysed at 1000 °C in N2 for 2 h to form amorphous Si-C-N-O followed by high energy milling for 1 h. Milled amorphous Si-C-N-O was sintered in hot pressing at 1600 and 1700 °C for 1 h in vacuum under the applied pressure of 50 MPa. Although no sintering additives were used, dense SiC-based composites were obtained with this method. Sintered density was 3.04 g/cm3, while only 2.57 g/cm3 for amorphous Si-C-N-O without milling. It is suggested that the liquid phase generated during the formation of Si2N2O facilitated the densification of the composite.
Mechanical Alloying-assisted Coating of Fe–Al Powders on Steel Substrate Noviyanto, Alfian; Harjanto, Sri; Widayatno, Wahyu Bambang; Wismogroho, Agus Sukarto; Amal, Muhamad Ikhlasul; Rochman, Nurul Taufiqu
Makara Journal of Technology Vol. 24, No. 3
Publisher : UI Scholars Hub

Show Abstract | Download Original | Original Source | Check in Google Scholar

Abstract

The coating layer of Fe–Al powders on the steel substrate was prepared by mechanical alloying at room temperature. Fe, Al, and the steel substrates were milled with high-energy ball milling for 32 h with a ball-to-powder ratio of 8 in an argon atmosphere to prevent oxidation during milling. Although mechanical alloying was performed for 32 h, no new phases were observed after mechanical alloying, as analyzed by X-ray diffraction. However, the crystallite size of the milled powders for 32 h decreased by factor two compared with the initial powders. Scanning electron micrographs showed that the coating layers formed >8 h after mechanical alloying. The intermetallic Fe3Al formed after the substrate was annealed at 500 ℃.
High-temperature failure of steel boiler tube secondary superheater in a power plant Sulthoni Akbar; Desrilia Nursyifaulkhair; Leanddas Nurdiwijayanto; Alfian Noviyanto; Nurul Taufiqu Rochman
SINERGI Vol 27, No 1 (2023)
Publisher : Universitas Mercu Buana

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22441/sinergi.2023.1.001

Abstract

This work investigated the failure analysis of the boiler tube secondary superheats in a power plant utility. The tube was composed of low carbon steel with 2.25Cr-1Mo addition, which was ruptured after a 26 h working test. The investigation of the tube’s failure was performed through several analysis, such as microstructure, elemental analysis, and mechanical test. It was found the abrupt increase in the operating temperature as the primary factor of the material degradation of the tube. The microstructure analysis shows the existence of elongated grain with the formation of microcracks on the grain boundaries, indicating the exceeded stress applied in the material. The hoop stress in the ruptured tube was 42.47 MPa, which is higher than the allowable stress of 23.5 MPa at 605 °C. Furthermore, the equiaxed grain was observed in the unruptured tube, implying the microstructural change after exposure at high temperatures.
Stabilitasi Fasa Kalsium Pirofospat Pada Temperatur Tinggi Dengan Penambahan Zirkonia Huda, Ihsanul; Kusumaningrum, Retno; Sukmarani, Galuh; Noviyanto, Alfian
Syntax Literate Jurnal Ilmiah Indonesia
Publisher : CV. Ridwan Publisher

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (1608.726 KB) | DOI: 10.36418/syntax-literate.v5i5.1134

Abstract

Kalsium Pirofospat adalah biomaterial yang sangat baik untuk digunakan sebagai pengganti tulang atau gigi yang rusak ataupun retak. Kalsium Pirofospat bersifat biokompatibel, bioaktif dan memiliki komposisi kimia yang mendekati komposisi pada tulang dan gigi manusia. Namun biomaterial ini memiliki kekurangan yaitu sifat mekanisnya yang rendah apabila digunakan untuk menerima beban yang berat. Peningkatan sifat mekanik kalsium pirofospat dapat dilakukan dengan menambahkan material zirkon. Oleh karena itu, pada penelitian ini dilakukan kajian perubahan fasa kalsium pirofospat dengan penambahan zirkon pada temperatur tinggi. Komposisi zirkonia yang ditambahkan sebesar 5% dan 10% (w/w). Pencampuran kalsium pirofosfat dilakukan menggunakan High Energy Milling (HEM) dengan Ball Powder Ratio (BPR) sebesar 5:1 selama 30 menit. Campuran selanjutnya dipanaskan pada temperatur 1000 selama 60 menit. Hasil karakterisasi menggunakan XRD menunjukan bahwa perlakuan pemanasan dapat mendekomposisi kalsium pirofosfat dan terbentuknya CaZrO3. Pemanasan juga menyebabkan ukuran partikel semakin besar. Hasil SEM menunjukkan ukuran mikrostruktur CPP TA yang semula 590±43nm menjadi CPP TAZ5 1,212±268µm dan CPP TAZ10 1,324±384µm. Sedangkan untuk CPP TB yang semula 455±32nm menjadi CPP TBZ5 1,112±546µm dan CPP TBZ10 1,123±392µm. Kata kunci: Kalsium Pirofospat, Zirkonia, High Energy Milling
Influence of Al and Cu Doping on the Structure, Morphology, and Optical Properties of ZnO Thin Film Faras Afifah; Arif Tjahjono; Aga Ridhova; Pramitha Yuniar Diah Maulida; Alfian Noviyanto; Didik Aryanto
Indonesian Journal of Chemistry Vol 23, No 1 (2023)
Publisher : Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22146/ijc.73234

Abstract

In this study, ZnO thin films doped with Al (AZO) and Cu (CZO) were fabricated on a glass substrate via sol-gel spin coating. The influence of 1 atomic % Al and Cu doping on the structure, morphology, as well as optical properties of ZnO thin film was then analyzed with X-ray diffraction (XRD), atomic force microscopy (AFM), and UV-Vis spectroscopy. XRD analysis revealed that all samples possessed hexagonal wurtzite crystal structures with 3 to 4 preferred orientations. Al and Cu doping caused a decrease in crystal size, while the lattice strain (e) and dislocation density (ρ) were increased. AFM indicated that Al and Cu doping reduced the surface roughness of the ZnO thin film. Optical measurement showed that all samples exhibited high transmittance (> 80%) in the visible light region. Transmittance was reduced after doping, while the band gaps for ZnO, AZO, and CZO thin films are 3.26, 3.28, and 3.23 eV. This study showed that an addition of 1 atomic % transition metal (Al and Cu) greatly influences the structure, morphology, and optical properties of ZnO thin film.