Correlations between Structural and Hardness of Fe-50%Al Coating Prepared by Mechanical Alloying

Fe-50%Al coatings were deposited on the surface of low-carbon steel using mechanical alloying technique atdifferent milling times. The correlation between structure and hardness of coating before and after heat treatment wasinvestigated. At the milling time of less than 180 min, the coating has an elongated lamellar structure. The size of elongatedlamellar structure decreased with increasing milling times which led to an increase in the hardness value of coating. Afterheat treatment, the coating transformed to FeAl intermetallic phase with a denser structure and uniform in the composition. Itaffected the hardness of coating. The hardness value of all samples after heat treatment was higher than coating after milling.The hardness of coating was strongly influenced by the morphology and phase of coating

EFFECTS OF CURING TEMPERATURE AND ATMOSPHERE ON THE PROPERTIES OF ISOTROPIC BONDED NdFeB MAGNETS.

EFFECTS OF CURING TEMPERATURE AND ATMOSPHERE ON THE PROPERTIES OF ISOTROPIC BONDED NdFeB MAGNETS. The purpose of this paper was to synthesize the isotropic bonded NdFeB magnets at varying curing temperature and atmosphere, and to clarify their properties. For the aforesaid objective, the NdFeB powder was mixed with polyacrylate binder (3wt%) and compacted by hydraulic pressure with a compressive pressure of 30 MPa. The specimens were then separately cured at 100, 150, 180 and 200°C for 1 h in air and vacuum. The effects of curing temperature in air and vacuum on the bulk density and magnetic properties of isotropic bonded NdFeB magnets were studied. The results indicated that the bulk density and fluxmagnet density of bonded NdFeB magnets decreased with increase in curing temperature. This seems to be due to the binder vaporization and oxidation of element of NdFeB magnet. The bulk density of specimens cured in air was higher than that in vacuum for all temperatures. On the contrary, the magnetic flux density showed the opposite behavior. The optimum magnetic properties were achieved at curing temperature of 100oC for 1 h in vacuumwith Br = 6,61 kG, HCJ = 8,841 kOe, and BHmax = 9,01 MGOe

Correlations Between Structural and Hardness of Fe-50%Al Coating Prepared by Mechanical Alloying

Fe-50%Al coatings were deposited on the surface of low-carbon steel using mechanical alloying technique atdifferent milling times. The correlation between structure and hardness of coating before and after heat treatment wasinvestigated. At the milling time of less than 180 min, the coating has an elongated lamellar structure. The size of elongatedlamellar structure decreased with increasing milling times which led to an increase in the hardness value of coating. Afterheat treatment, the coating transformed to FeAl intermetallic phase with a denser structure and uniform in the composition. Itaffected the hardness of coating. The hardness value of all samples after heat treatment was higher than coating after milling.The hardness of coating was strongly influenced by the morphology and phase of coating

PEMILIHAN MATERIAL PELAPISAN UNTUK PENINGKATAN DAYA TAHAN BILAH TURBIN PESAWAT

Pendekatan material baru yang canggih adalah mutlak untuk menjawab tantangan wahana udara pada masa kini. Adanya beban struktural dan keadaan ekstrim pada saat beroperasi meliputi temperatur dan tekanan tinggi menjadi parameter utama dalam pemilihan material baru yang akan digunakan. Penelitian ini menyajikan pemilihan kandidat material yang cocok untuk penghalang termal pada bilah turbin pesawat. Berbagai kegagalan bilah turbin yang selama ini dialami diantaranya ketahanan termal, oksidasi suhu tinggi, dan kelelahan siklus tinggi yang kemudian dijadikan acuan dalam melakukan pemilihan material baru. Didapati paduan superalloy berbasis nikel memiliki batasan dalam kinerja temperatur tinggi dan ketahanan fisik yang tinggi dari komposit menjadi perhatian khusus, karena merupakan properti utama yang fokus untuk aplikasi bilah pada mesin turbin gas pesawat terbang. Sehingga dilakukan komposit dengan material baru yang kuat pada kondisi operasi pada 12000C, yakni material dengan struktur keramik seperti SiC dan Si3N4 serta material dengan sturktur silisida seperti MoSi2

Studi X-ray Diffractometry pada Struktur Coating Alumunium yang Dipreparasi Denganmetode Mechanical Alloying

X-RAY DIFFRACTOMETRY STUDY ON STUCTURE OF ALUMINUM COATING PREPARED BY A MECHANICAL ALLOYING METHOD. Aluminum (Al) coating was successfully deposited on the surface of low carbon steel by using a mechanical alloying method. After coating deposition, the aluminum coating was annealed in vacuum furnace of 5.6 Pa at elevated temperatures of 600 oC, 700 oC and 800 oC. Phase transformation and structure changes in aluminum coating at varying curing temperatures ware studied by means of X-ray diffraction (XRD). The presence of Al (111) diffraction peak from the results of XRD characterization indicates thatAl coating was deposited on the surface of low carbon steel. On the other hand, the results of XRD characterization show the phase transformation and structure changes of Al coating due to the effect of annealing temperature. It was indicated by the presence of diffraction peaks of Al3,2Fe, Fe3Al, dan Fe0,8Al0,2 after annealing.An increase in annealing temperature leads to decrease in d-spacing, lattice parameter, and lattice constant Fe0,8Al0,2(110). However, the lattice strain and dislocation density are likely to increase. Structure coating evolution occurred due to the diffusion of aluminum to the substrate of low carbon steel

Crystal Structure Transformation of Ba-sr Hexaferrite and Its Effect on Particle Orientation in Recycle Process

CRYSTAL STRUCTURE TRANSFORMATION OF Ba-Sr HEXAFERRITE AND ITS EFFECT ON PARTICLE ORIENTATION IN RECYCLE PROCESS. In general, during its fabrication, 2-5%of total products of Ba-Sr hexaferrite permanent magnet will be rejected.Accordingly, an increase in rejected product of permanent magnet needs to be considered. It is expected that the re-utilization of rejected product can increase the production efficiency in order to achieve zero waste-production. In the present work, the recycling process of Ba-Sr hexaferrite permanent magnet was studied by applying 1 T magnetic field (anisotropic) to align the powder. The rejected products were milled using shaker mill PPF-UG for 10-40 min and then sintered at 1200 ºC for 60 min. The results show that the remanence of original powder was increased by 50% after the particle orientation. However, the recycled sample doesn't show a significant different. SEM and XRD analysis show the crystalline structure transformation from symmetrical hexagonal to asymmetrical hexagonal structure with crystalline growth in a-b axis direction. This transformation leads to lost in its magneto crystalline anisotropy. Therefore, it was difficult to align the particle

STUDI X-RAY DIFFRACTOMETRY PADA STRUKTUR COATING ALUMUNIUM YANG DIPREPARASI DENGAN METODE MECHANICAL ALLOYING

STUDI X-RAY DIFFRACTOMETRY PADA STRUKTUR COATING ALUMUNIUM YANG DIPREPARASI DENGAN METODE MECHANICAL ALLOYING. Coating alumunium (Al) telah berhasil dideposisikan pada permukaan baja karbon rendah (low carbon steel) dengan menggunakan metode pemaduan mekanik (mechanical alloying). Setelah dideposisikan, coating alumunium diannealing di dalam vacum furnace pada suhu 600 oC, 700 oC dan 800 oC dengan kondisi vakum sekitar 5,6 Pa. Transformasi fasa dan perubahan struktur pada coating alumunium sebagai fungsi suhu annealing dipelajari dengan menggunakan teknik difraksi sinar-X (XRD). Puncak difraksiAl(111) dari hasil karakterisasi XRD mengindikasikan bahwa coating alumunium telah terdeposisi pada permukaan low carbon steel. Selain itu, hasil XRD juga menunjukkan transformasi fasa dan perubahan struktur coating alumunium sebagai efek suhu annealing. Hal itu ditandai dengan munculnya fasa Al3,2Fe, Fe3Al, dan Fe0,8Al0,2 pada pola difraksi XRD setelah diannealing. Peningkatan suhu annealing menyebabkan penurunan d-spacing, parameter kisi dan konstanta kisi kristal Fe0,8Al0,2(110), namun terjadi peningkatan pada regangan kisi dan kerapatan dislokasi. Evolusi pada struktur coating terjadi karena difusi alumunium kedalam low carbon steel

HEAT TREATMENT BAJA TAHAN KARAT AISI 430, KAJIAN MICROSTRUCTURE AND HARDNESS SEBAGAI MATERIAL BIOMEDIS

The heat treatment of AISI-430 steel was carried out in inert gas Nitrogen atmosphere at 1200 C and elevated pressures of 300, 400 and 500 Psi for 5 and 7 hours, respectively. In this experiment, the microstructure and hardness (HV) of the sample were analyzed. The structure analysis consists of optical microscope, scanning electron microscope equipped with energy dispersive X-ray spectometer (SEM-EDS) and X-ray diffraction (XRD). The results show that the optimum condition for the heat treatment was achieved at o 1200C for 7 h and inert gas Nitrogen pressure of 500 Psi. At the aforesaid condition, the Nitrogen element was uniformly distributed on the sample surface with concentration of 29.7 wt%. The fraction of austenitic phase is about 9.69 wt% and the hardness of material increases from 161.8 to 547.15 HV. The results of this study suggests that the materials can be considered to be used for biomedical applications as implant material.  Keywords: austenite, heat treatment, high resistant steel AISI-430, biomedical, Nitrogen

CRYSTAL STRUCTURE TRANSFORMATION OF Ba-Sr HEXAFERRITE AND ITS EFFECT ON PARTICLE ORIENTATION IN RECYCLE PROCESS

CRYSTAL STRUCTURE TRANSFORMATION OF Ba-Sr HEXAFERRITE AND ITS EFFECT ON PARTICLE ORIENTATION IN RECYCLE PROCESS. In general, during its fabrication, 2-5%of total products of Ba-Sr hexaferrite permanent magnet will be rejected.Accordingly, an increase in rejected product of permanent magnet needs to be considered. It is expected that the re-utilization of rejected product can increase the production efficiency in order to achieve zero waste-production. In the present work, the recycling process of Ba-Sr hexaferrite permanent magnet was studied by applying 1 T magnetic field (anisotropic) to align the powder. The rejected products were milled using shaker mill PPF-UG for 10-40 min and then sintered at 1200 ºC for 60 min. The results show that the remanence of original powder was increased by 50% after the particle orientation. However, the recycled sample doesn’t show a significant different. SEM and XRD analysis show the crystalline structure transformation from symmetrical hexagonal to asymmetrical hexagonal structure with crystalline growth in a-b axis direction. This transformation leads to lost in its magneto crystalline anisotropy. Therefore, it was difficult to align the particle

EFFECT OF Mn-Ti IONS DOPING AND SINTERING TEMPERATURE ON PROPERTIES OF BARIUM HEXAFERRITE

EFFECT OF Mn-Ti IONS DOPING AND SINTERING TEMPERATURE ON PROPERTIES OF BARIUM HEXAFERRITE. Mn-Ti doped (0, 0.1, 0.4, 0.5, and 0.6 mole%-barium hexaferrite powders have been prepared from BaCO3, Fe2O3, TiO2 andMnO powder by mechanical alloying technique for 20 hours. The mixture powder were grinded and then dried at 100 °C for 24 hours, followed by calcined at 1,000 °C for 2 hours. The calcined powder was then crushed into 400 mesh (38 μm) in particle size. X-Ray Diffraction analysis was performed to determine the phase formed. The powder was mixed with 3 wt%Celuna WE -518 polymer, and compressed with applied force of 5 tons. The sintering process was done at temperatures of 1100 °C and 1150 °C for 2 hours. The microstructure of sintered samples was observed by Scanning Electron Microscope - Energy Dispersive X-Ray Spectroscopy (SEM-EDS). The magnetic properties and Reflection Loss (RL) was measured by permeagraph Magnet-Physik and Vector Network Analyzer (VNA), respectively. The results show that the remanance (Br) of samples are likely to decrease with increase in %mol of Mn-Ti and the optimum coercivity (HCJ) 4,42 kOe was achieved at 0,5 mole% Mn-Ti. The maximum reflection loss of -25,6 dB was obtained at 0,4mole%Mn-Ti with sintering temperature of 1100 °C for 2 hours. Accordingly, it can be potentially used for microwave absorption application