Abstract.Magnesium and its alloy have gained a lot of interest to be used in biomedical application due to its biodegradable and biocompatible properties. In this study, sintering process in powder metallurgy was chosen to fabricatenonporous Mg-6Zn-1Ca (in wt%) alloy and porous Mg-6Zn-1Ca-10Carbamide alloy. For creating porous alloy, carbamide (CO(NH ) was added to alloy system as the space holder to create porous structure material. Effect of the space holder addition and sintering temperature on porosity, phase formation, mechanical properties, and corrosion properties was observed.Sintering process was done in a tube furnace under Argon atmosphere in for 5 hours. The heat treatment was done in two steps; heated up at 250 ºC for 4 hours to decompose spacer particle, followed by heated up at 580 ºC or 630 ºC for 5 hours. The porous structure of the resulted alloys was examined using Scanning Electron Microscope (SEM), while the phase formation was characterized by X-ray diffraction (XRD)analysis. Mechanical properties were examined using compression testing. From this study, increasing sintering temperature up to 630 ºC reduced the mechanical properties of Mg-Zn-Ca alloy.
This study aims to construct prototypes using three-dimensional (3D) printing technology as a research apparatus and a physics education instrument, particularly in medical physics education. Two main designs of prototypes have been arranged. Two foam NaCl templates are drawn using computer-aided design (CAD) software. Image processing techniques achieve a 3D model of a thoracic vertebra. All 3D model data are printed using polylactic acid (PLA) filament. The prints of foam NaCl templates are utilized for holding the NaCl powder. The prototype of a human vertebra is used for visualization of the real condition of the human bone anatomy. The results of the prototypes are analyzed to investigate the similarity between the model and the prints. This investigation is done using a Vernier Caliper and CT Scan. The measurement using Caliper shows a higher percentage in likeness than the CT-Scan. All the accuracy study shows they have more than 83% in similarity. It can be concluded that all built prototypes have prominent exactitude and can support the material research using the printed NaCl templates. Hereafter, a bone mock-up’s genuine perception can function for further application, such as implant or surgery planning.
Magnesium alloy is a material that has been developed as a biodegradable implant material in orthopedic applications. Magnesium alloys have good biocompatibility, biodegradability, and good mechanical properties which make them have the potential to be used as a biomedical material. The main objective of this paper is to investigate corrotion rate and morphology after corrotion of biocompatibility of implant-based alloys Mg-Ca-Zn with CaCO 3 as a foaming agent. Mg-Ca-Zn Alloy was made by the method of powder metallurgy with the addition of CaCO 3 as a foaming agent with three variations of composition (96Mg-Ca-3Zn-CaCO 3 , 91Mg-Ca-3Zn-5CaCO 3 ,and 86Mg-Ca-3Zn-10 CaCO 3 wt%). Sintering process was carried out at 600 °C and 650 °C with a holding time of five hours. Corrosion test was performed using G750 Gamry Instrument in accordance with ASTM standard G5-94. Simulated body fluid electrolyte used is Hank's solution with a pH value of 7.4 and a temperature of 37 °C. Then the analysis of the microstructure after corrosion test was conducted using scanning electron microscopy (JEOL, JSM-6390A Japan) equipped with energy dispersive spectrometry data (EDS). Alloy corrosion rate of Mg-Ca-Zn-CaCO 3 increases with the amount of CaCO 3 in the alloy and the temperature rise in the sintering. From the test results, the smallest corrosion rate is in the alloy 91Mg-Ca-3Zn-CaCO 3 at 600 °C sintering (58.3045 mpy) and the highest occurs in alloy 86Mg-Ca-3Zn-10CaCO 3 at 650 °C sintering (91.4007 mpy). Surface morphology of the alloy after the corrosion process is the type of volcano. This localized corrosion occurs where an electrochemical reaction takes place to form a distinctive structure with a circle and a hole in the middle.
Graphene oxide and reduced graphene oxide attract a lot of attention due to graphene provides some properties that suitable for wider application. Properties of graphene are unique since it can be tuned regarding to its controlled synthesis method and several treatments. This work, graphene oxide was synthesized from used graphite electrode by modified Hummer’s method in which oxidation process controlled. Zinc was used to produce reduced graphene oxide. Graphene oxide and reduced graphene oxide were characterized by SEM, EDS, FT-IR, UV-vis, and XRD. Effective strategy was studied to produce graphene oxide and reduced graphene oxide by controlling its oxidation process. These results prove that chemical and structural properties of graphene oxide and reduced graphene oxide depend on oxidation duration. Furthermore, carbon/oxygen ratio was studied to evaluate effective oxidation process.
Powder metallurgy has been developed to fabricate metal foams from various materials including magnesium. One particular challenge on powder metallurgy is fabrication of highly-ordered and interconnected porous products. Pores interconnectivity is important in application of porous magnesium alloy for biodegradable orthopedic implants. Meanwhile, 3D polymeric printing technology offers capability to build precise and rapid lattice wireframe products in a simple and low-cost manner. Here, we design and validate the capability of 3D polymeric lattice as template in powder metallurgy for fabrication of magnesium-based biodegradable implants. Lattice structures were made of ABS, PLA, and PVA filaments. Lattice structures were cubical-shaped with uniform dimension and variations in pore size are included in the study. Both computational and experimental tests are performed to determine the compressive strength of the lattice structures. Uniaxial stress with uniform magnitude is applied to test the lattice structures. The resulting stress, strain, and deformation of the 3D polymeric lattice are observed. Variations in materials and pore size affect the stress, strain and deformation of the 3D polymeric lattice. Parameters can be further optimized to meet the requirement of the design and fabrication process in consideration of the tolerable stress, strain and deformation.
Paduan logam berpori berbasis magnesium sangat potensial dalam aplikasi prostesis biomedis. Kalsium, seng dan agen pengembang ditambahkan untuk melengkapi fungsi dan aplikasi paduan. Dalam studi ini, paduan logam berpori Mg-Ca-Zn dikembangkan dengan proses metalurgi serbuk menggunakan dolomit (CaMg(CO 3 ) 2 ) sebagai agen pengembang untuk menghasilkan pori jenis tertutup. Variasi ukuran agen pengembang dan temperatur sintering dilakukan dengan tujuan untuk mencapai ukuran, persentasi dan kehomogenan pori yang terbentuk dalam paduan, dimana pori berfungsi untuk pertumbuhan tulang baru. Komposisi (%berat) paduan yang dikembangkan adalah 84,5Mg-0,5Ca-5Zn-10CaMg(CO 3 ) 2 , dengan variasi temperatur sintering T = 650, 675, dan 700°C dan waktu tahan 5 jam, sedangkan ukuran dolomit CaMg(CO 3 ) 2 divariasikan -30 #, -50 #, -80 #. Paduan hasil sintering diuji XRD (x-ray diffraction) untuk menganalisis fasa yang terbentuk. Ukuran dan kehomogenan pori hasil sintering diamati dengan SEM (scanning electron microscopy), dan persentasi pori yang terbentuk diukur dengan menggunakan metode Archimedes sesuai standar ASTM B311-93. Sifat mekanik dari paduan hasil sintering diuji dengan alat uji kompresi mengacu pada standar ASTM D-695-02. Analisis XRD (x-ray diffraction) dalam paduan 84,5Mg-0,5Ca-5Zn-10CaMg(CO 3 ) 2 hasil sintering terbentuk fasa Mg sebagai matriks, MgO, CaCO 3 dan dolomit (CaMg(CO 3 ) 2 ). Persentasi porositas tertinggi diperoleh sebesar 32,60% dengan ukuran pori terbesar adalah ≤300 μm dan kekuatan tekan 143 MPa. Kondisi ini dihasilkan dalam paduan dengan ukuran partikel dolomit -30# dan temperatur sintering 700°C. Teknologi metalurgi serbuk dengan variasi temperatur sintering dan variasi ukuran agen pengembang dolomit berpengaruh signifikan terhadap ukuran, persentasi, dan kehomogenan pori serta sifat mekanik yang dihasilkan dalam paduan 84,5Mg-0,5Ca-5Zn.Kata kunci: logam berpori tertutup; biomaterial; paduan 84,5Mg-0,5Ca-5Zn; agen pengembang dolomit (CaMg(CO 3 ) 2 ); metalurgi serbuk Abstract [Title: Sintering Temperature and Size Variation Analysis of Dolomite Development Agency to Closed Pores Mg-Ca-Zn Metal Alloy Fabrication by Powder Metallurgy Process]Magnesium-based porous metal alloys have great potential in biomedical prosthesis applications. Calcium, zinc, and a foaming agent are added to complement the function and application of the alloy. In this study, Mg-Ca-Zn porous metal alloy was developed by powder metallurgy process and using dolomite (CaMg(CO3)2) as a foaming agent to produce a closed pore type. Various sizes of the foaming agent and the sintering temperatures are carried out to achieve the size and homogeneity of the pores formed in the alloy, where the pores function for new bone growth. The alloy's composition (wt%) was 84.5Mg-0.5Ca-5Zn-10CaMg(CO3)2, with different sintering temperatures T = 650, 675, and 700 °C and holding time of 5 hours, while the size of
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