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Abstrak :
Salah satu teknik pengubahan bentuk yang dapat digunakan untuk menghaluskan butir adalah teknik Equal Channel Angular Pressing (ECAP), salah satu dari metode Severe Plastic Deformation (SPD). Dalam penelitian ini ECAP dilakukan pada material kuningan alfa atau cartridge brass, material yang memiliki ketangguhan dan mampu bentuk yang baik. ECAP dilakukan melalui penekanan pada material dalam dies untuk meningkatkan sifat mekanis dari material. Deformasi plastik yang terjadi pada material saat proses penekanan sangat dipengaruhi oleh geometri dari cetakan, oleh karena itu dipilih sudut 120º pada dies ECAP. Hasil dari studi ini adalah didapatnya peningkatan kekerasan dari 73 HV menjadi 210 HV, dan penurunan diameter butir dari 34 μm menjadi 6,85 μm melalui ECAP sebanyak 3 kali laluan dengan besar peregangan 1,90.

Abstrak :
ABSTRAK
Penerapan magnesium sebagai implan merupakan salah satu pemanfaatan dari natur biomaterial dari magnesium sendiri. Berbagai usaha untuk meningkatkan resistansi terhadap laju korosi yang terlalu besar, yang menjadi kelemahan dari magnesium telah dilakukan, contohnya adalah penggunaan metode ECAP. Penelitian ini membahas mengenai proses manufaktur dari implan berbahan dasar magnesium ECAP, secara khusus implan jenis miniplate. Metode fabrikasi micro-forming, terbukti dapat dengan akurat memfabrikasi miniplate sesuai dengan design yang diajukan, dengan rerata error terbesar ada pada bagian thickness atau ketebalan plat. Error yang ada cukup kecil pada angka 12.43 . Bagian yang paling krusial, yaitu hole, memiliki akurasi serta presisi yang baik, dengan rerata error 1.43 , yang paling kecil dari seluruh detail yang diukur. Kalkulasi yang telah dibuat berdasarkan physical properties dari magnesium juga terbukti sesuai dengan trial yang dilakukan sehingga hasil cukup akurat. <

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ABSTRACT
The use of magnesium as an implant material is the utilization of magnesium rsquo s nature as a biomaterial. Lots of methods are developed in an effort to inhibit magnesium rsquo s high degradation rate, which is one of magnesium rsquo s weakness. One of such method is the ECAP. This research is focused on the manufacturing process of magnesium ECAP based implant, especially the maxilla miniplate. The micro forming fabrication method is proven to be accurate enough to fabricate the miniplates according to the original design, with the largest error being the thickness of the plate. plat. The largest error occurred in this research is 12.43 , which is quite small. The most crucial part, the hole, proved to be quite accurate and precise, with 1.43 average error, which is the smallest error in the detail. The calculation based on the physical properties of magnesium is also accurate enough to be used as the basis for the manufacturing rsquo s parameters.

Abstrak :
The present study investigated the mechanical properties and microstructure of ultrafine grained (UFG) brass processed by four passes of equal channel angular pressing (ECAP) and annealed at elevated temperatures. The mechanical properties of all samples were assessed using tensile and micro-hardness tests. Microstructure analysis was performed using optical microscopy (OM) and scanning electron microscopy (SEM). Ultimate tensile strengths (UTS) and yield strengths (YS) of 878 and 804 MPa, respectively, ductility of 15%, and hardness of 248 HV were obtained for samples processed by four passes of ECAP with equivalent true strain of 4.20. Annealing at 300°C caused UTS and YS to decrease significantly, to 510 and 408 MPa, respectively, ductility to increase to 28%, and hardness to decrease to 165 HV. Fractography analysis of un-annealed samples after four ECAP passes showed small brittle fractures with shallow dimpling. Ductile failures were found on annealed samples. After four ECAP passes, the microstructure of un-annealed samples was UFG and dominated by lamellar grain with shear band. In contrast, after annealing, the microstructure changed due to recrystallization, showing nucleation and grain growth.

Abstrak :
The present study investigated the mechanical properties and microstructure of ultrafine grained (UFG) brass processed by four passes of equal channel angular pressing (ECAP) and annealed at elevated temperatures. The mechanical properties of all samples were assessed using tensile and micro-hardness tests. Microstructure analysis was performed using optical microscopy (OM) and scanning electron microscopy (SEM). Ultimate tensile strengths (UTS) and yield strengths (YS) of 878 and 804 MPa, respectively, ductility of 15%, and hardness of 248 HV were obtained for samples processed by four passes of ECAP with equivalent true strain of 4.20. Annealing at 300°C caused UTS and YS to decrease significantly, to 510 and 408 MPa, respectively, ductility to increase to 28%, and hardness to decrease to 165 HV. Fractography analysis of un-annealed samples after four ECAP passes showed small brittle fractures with shallow dimpling. Ductile failures were found on annealed samples. After four ECAP passes, the microstructure of un-annealed samples was UFG and dominated by lamellar grain with shear band. In contrast, after annealing, the microstructure changed due to recrystallization, showing nucleation and grain growth.

Abstrak :
Mechanical alloying (MA) was used to produce Ti-xMg alloys (x = 0, 2.5, 5, 7.5, 10 wt%Mg), and powders alloys of Ti-Mg were characterized by X-ray diffraction and Optical microscope. Investigation shows that the homogenous structure have not yet been obtained as milling Ti and Mg for 4 hours, but XRD traces indicated that mechanical alloying have produced Ti-Mg alloys as Mg peaks has disappeared from the traces. XRD results also showed that mechanical alloying and addition of Mg have direct effect on XRD broadening. Powder alloys were compacted using severe plastic deformation method, ECAP. Using Archimedes principle the density of Ti-Mg solid samples were measured and results shows that the density decreased as Mg content increases. Relative density on compacted powders indicates that ECAP has produced in excess of 98% density on each sample, and annealing improved the density. Microstructure observation using SEM shows that ECAP has produced good inter-particles boundaries as well as some porosity and undissolved Mg particles can be observed. After annealing there is improvement in boundaries in samples containing Mg, but at the same time cause segregation of Mg, which indicates diffusion of Mg occurs faster during annealing at 600_C. Mechanical properties measurement was conducted by ball indentation test method on annealed and un-annealed bulk samples, and the result were studied and analysed carefully, however, the final result of mechanical properties were not well understood and still require further and deeper investigation in the future.

Abstrak :
ABSTRAK
Latar Belakang Pada penatalaksanaan fraktur maksilofasial secara internal fiksasi diperlukan pemasangan alat miniplate dan screw sampai terjadi penyembuhan tulang Magnesium memiliki potensi sebagai miniplate dan screw pada tulang rahang dengan syarat bersifat biokompatibel dan biodegradasi sehingga tidak diperlukan operasi kembali untuk pengambilan miniplate dan screw Proses equal channel angular pressing ECAP merupakan salah satu metode untuk mengontrol laju korosi logam magnesium dan meningkatkan sifat mekanisnya Untuk pembuatan desain miniplate dan screw dari magnesium ECAP dengan merujuk dari desain safety factor bahan titanium yang biasanya telah digunakan perlu disesuaikan dengan material properti magnesium agar dapat mencegah kerusakan Tujuan menganalisa perbandingan desain miniplate dan screw logam magnesium ECAP terhadap titanium Metode Untuk penelitian ini kami menggunakan metode finite elemen yaitu formulasi perpindahan untuk menghitung perpindahan komponen strain dan tekanan di bawah beban internal dan eksternal Kemudian desain miniplate dan screw dari magnesium ECAP dilakukan analisa simulasi pembebanan yang dianalisa menggunakan teori Von Misses Hasil Hasil desain miniplate dan screw magnesium ECAP yang diharapkan dapat digunakan pada penatalaksanaan fraktur maksilofasial telah dilakukan simulasi pembebanan dengan dilakukan analisa desain menggunakan teori Von Misses kemudian desain direkayasa untuk mengurangi stress yang diterima desain rekayasa magnesium ECAP dibuat menjadi dua tipe yaitu tipe 1 dengan menambah jumlah screw menjadi 8 screw dengan berat total miniplate dan screw sebesar 118 212 mg dan tipe ke 2 dengan merubah diameter head screw menjadi 2x lebih besar dari bentuk semula sehingga berat totalnya sebesar 169 414 mg Kesimpulan Desain alternatif miniplate dan screw magnesium ECAP tipe 1 dapat lebih efektif untuk digunakan pada penatalaksanaan fraktur maksilofasial ABSTRACT
Background In the internal fixation management of maxillofacial fractures the placement of miniplate and screw is necessary until bone repair takes place Magnesium has the potential as a miniplate and screw for the jaws with it rsquo s biocompatibility and biodegradability so that a follow up surgery to remove the miniplate and screw is not necessary The equal channel angular pressing ECAP process is a method to control the corrosion rate of magnesium and increase the mechanical properties In the making of miniplate and screw design from ECAP magnesium referring the safety factor of the titanium design that is already being used adjustments must be made with the characteristics of magnesium so damage can be avoided Objectives to analyze the comparison between magnesium ECAP miniplate and screw design against titanium Methods For this research we used the finite element method which is displacement formulation to calculate component movement strain and pressure under the internal and external load Afterwards the magnesium ECAP miniplate and screw design undergoes a loading simulation which is analyzed with the Von Misses theory Result Design of miniplate and screw magnesium ECAP which expected to be used in the management of maxillofacial fractures has been tested with the stress simulation using Von Misses theory then the design engineered to reduce stress received Engineering design of magnesium ECAP divided into two types type 1 by increasing the number of screw into 8 screws with a total weight miniplate and screws with a total weight miniplate and screw amounted to 118 212 mg and type 2 by changing the diameter of the head screw becomes large than its original shape so that the total weight of 169 414 mg Conclusion Design alternative of miniplate and screw magnesium ECAP type 1could be more effective to be used in the management of maxillofacial fracture ;Background In the internal fixation management of maxillofacial fractures the placement of miniplate and screw is necessary until bone repair takes place Magnesium has the potential as a miniplate and screw for the jaws with it rsquo s biocompatibility and biodegradability so that a follow up surgery to remove the miniplate and screw is not necessary The equal channel angular pressing ECAP process is a method to control the corrosion rate of magnesium and increase the mechanical properties In the making of miniplate and screw design from ECAP magnesium referring the safety factor of the titanium design that is already being used adjustments must be made with the characteristics of magnesium so damage can be avoided Objectives to analyze the comparison between magnesium ECAP miniplate and screw design against titanium Methods For this research we used the finite element method which is displacement formulation to calculate component movement strain and pressure under the internal and external load Afterwards the magnesium ECAP miniplate and screw design undergoes a loading simulation which is analyzed with the Von Misses theory Result Design of miniplate and screw magnesium ECAP which expected to be used in the management of maxillofacial fractures has been tested with the stress simulation using Von Misses theory then the design engineered to reduce stress received Engineering design of magnesium ECAP divided into two types type 1 by increasing the number of screw into 8 screws with a total weight miniplate and screws with a total weight miniplate and screw amounted to 118 212 mg and type 2 by changing the diameter of the head screw becomes large than its original shape so that the total weight of 169 414 mg Conclusion Design alternative of miniplate and screw magnesium ECAP type 1could be more effective to be used in the management of maxillofacial fracture ;Background In the internal fixation management of maxillofacial fractures the placement of miniplate and screw is necessary until bone repair takes place Magnesium has the potential as a miniplate and screw for the jaws with it rsquo s biocompatibility and biodegradability so that a follow up surgery to remove the miniplate and screw is not necessary The equal channel angular pressing ECAP process is a method to control the corrosion rate of magnesium and increase the mechanical properties In the making of miniplate and screw design from ECAP magnesium referring the safety factor of the titanium design that is already being used adjustments must be made with the characteristics of magnesium so damage can be avoided Objectives to analyze the comparison between magnesium ECAP miniplate and screw design against titanium Methods For this research we used the finite element method which is displacement formulation to calculate component movement strain and pressure under the internal and external load Afterwards the magnesium ECAP miniplate and screw design undergoes a loading simulation which is analyzed with the Von Misses theory Result Design of miniplate and screw magnesium ECAP which expected to be used in the management of maxillofacial fractures has been tested with the stress simulation using Von Misses theory then the design engineered to reduce stress received Engineering design of magnesium ECAP divided into two types type 1 by increasing the number of screw into 8 screws with a total weight miniplate and screws with a total weight miniplate and screw amounted to 118 212 mg and type 2 by changing the diameter of the head screw becomes large than its original shape so that the total weight of 169 414 mg Conclusion Design alternative of miniplate and screw magnesium ECAP type 1could be more effective to be used in the management of maxillofacial fracture

Abstrak :
Latar Belakang: Magnesium ECAP mempunyai sifat mekanis yang baik danpengaruh osteoanabolik, namun magnesium memiliki sifat korosif.Imunohistokimia mengidentifikasi respon proses korosi dengan melihat jejakjaringan sekitar. Metode: Tulang femur dipasang miniplate dan screwdikelompokkan 1-3-5 bulan. Tulang kontrol diambil pada sisi berlawanan. Hasil Imunohistokimia dinilai dengan skoring. Data diuji nonparametrik dengan tingkatkepercayaan 99. Hasil: Perbedaan bermakna kelompok perlakuan dengankelompok kontrol p=0,000 . Peningkatan pembentukan trabekula dan responosteogenesis. Peningkatan revaskularisasi dan reaksi kluster diferensiasi terhadapgas poket hingga bulan ke-3. Kesimpulan: Respon jaringan sekitar tertoleransi dengan terjadinya peningkatan osteogenesis, tidak ditemukannya jaringannekrosis, dan penurunan nilai gas poket. ......Background : ECAP processed magnesium has an excellent mechanicalproperties and osteoanabolic effect. However metal materials are known to havecorrosive nature, and magnesium was no exception. Immunohistochemistry is ableto identify corrosion process response in living organism by looking into its tracesin surrounding tissus. Methods : The femur bone samples were implanted byECAP processed magnesium miniplate and screw for 1, 3, and 5 months. Theopposing femur was left alone as control samples. Afterwards,immunohistochemical staining results were scored and tested using nonparametrictests with confidence interval of 99. Results : Significant differences werefound between treatment groups and control groups p=0.000. The increase oftrabeculae formation and osteogenesis responses also revascularisation anddifferentiation clusters to gas voids are observed well into the 3 month samples. Conclusion : Surrounding tissue responses are tolerated as shown by the increaseof osteogenesis, untraceable necrotic tissues, and the decrease in gas voids score.

Abstrak :
Latar Belakang : Bahan Magnesium mempunyai potensi sebagai bahan biodegradasi untuk aplikasi di bidang bedah mulut dan maksilofasial karena mempunyai sifat dapat terdegradasi. Dengan sifat biodegradasinya, Magnesium mempunyai keuntungan dibandingkan bahan biodegradable lain yang sudah ada seperti polimer, keramik dan gelas bioaktif dimana kekuatannya cukup dan nilai modulus Young mendekati tulang. Namun, degradasi magnesium yang cepat akibat korosi di dalam tubuh makhluk hidup dapat membatasi aplikasi klinisnya, misalnya aplikasi di bidang bedah mulut dan maksilofasial, karena tingkat degradasi yang terlalu tinggi menyebabkan kerusakan fungsi yang dini. Equal Channel Angle Pressing (ECAP) adalah prosedur pembentuk bahan yang digunakan untuk mengeluarkan material dengan menggunakan saluran yang dirancang secara khusus tanpa menyebabkan perubahan geometri yang substansial dan dapat membuat bahan berbutir dengan ukuran yang mengecil dengan menerapkan teknik Severe Plastic Deformation. Tujuan : Pada penelitian ini kami menggunakan bahan Magnesium yang telah diproses dengan teknik Equal Channel Angular Pressing (ECAP) untuk produk screw. Kami mengembangkan model in vivo pada kelinci untuk menilai degradasi bahan Magnesium ECAP untuk aplikasi klinis di bidang bedah mulut dan maksilofasial. Metode : Empat sekrup ditanamkan ke tulang paha kanan masing-masing dari 10 kelinci. Kelompok ini dibagi dalam periode pengamatan 4, 12 dan 20 minggu. Densitas degradasi bahan dan keadaan biologis disekitar screw dianalisa menggunakan pemeriksaan Micro-Computed Tomography (Mikro-CT) dan pewarnaan histologis setelah necropsy kelinci. Hasil: Kami mengamati kehilangan volume pada semua screw, dengan timbulnya produk korosi. Nilai laju degradasi untuk screw ditemukan sebesar (0,49 ± 0,14 mm a-1). Kami juga menemukan perbedaan perilaku korosi antar bagian sekrup. Secara khusus, data kami menunjukkan bahwa korosi terjadi pada kepala dan batang screw. Kesimpulan : Hasil penelitian baru pada kelinci ini menunjukkan bahwa sekrup Magnesium ECAP ini dapat dipertimbangkan sebagai bahan alternatif dibandingkan dengan bahan implan konvensional. ......Background : Magnesium alloys have shown potential as biodegradable metallic materials for oral and maxillofacial surgery applications due to their degradability. Biodegradable magnesium are advantageous over existing biodegradable materials such as polymers, ceramics and bioactive glasses where sufficient strength and Young’s modulus close to that of the bone are required. However, fast degradation of magnesium due to corrosion in the human bio-environment may limit its clinical applications, for example, oral and maxillofacial surgery applications, because a too high degradation rate leads to premature deterioration of biofunctionality. Equal channel angular pressing (ECAP) is a viable forming procedure to extrude material by use of specially designed channel dies without a substantial change in geometry and to make an ultrafine grained material by imposing severe plastic deformation. Objectives : In this study we use Mg alloys processed by Equal Channel Angular Pressing (ECAP) for screw fabrication products. We developed an in vivo model in rabbits to assess Mg ECAP alloys degradation for oral and maxillofacial surgery applications. Methods : Four screws were implanted to the right femur of each of 10 rabbits. This group was divided into observation periods of 4, 12 and 20 weeks. Alloy degradation and biological effect were determined by Micro-computed Tomography (Micro-CT) and histological staining after sacrifice the rabbits. Results : We observed a net volume loss for all devices, with considerable corrosion product formation. A greater corrosion rate for the screws (0.49 ± 0.14 mm a-1). We also found differences in corrosion behavior between screw regions. Specifically, our data suggest that corrosion was enhanced for screw shafts compared to heads Conclusion : The results of this novel study in rabbits indicates that this screw Magnesium ECAP should be considered as an alternative to conventional implant materials.

Abstrak :
ABSTRAK
Pada penelitian ini, telah dilakukan proses SPD (Severe Plastic Deformation) dengan teknik ECAP (Equal Channel Angular Pressing) bersudut 900 pada material Cu-30%Zn. Proses ECAP dilakukan dengan memasukkan material pada cetakan yang kemudian diberikan penekanan dengan menggunakan mesin kompaksi hidrolik berkapasitas 40 Ton. Spesimen dilakukan proses ECAP sebanyak 3 kali passing dengan rute Bc. Pengamatan mikrostruktur dilakukan untuk mengetahui ukuran butir dan penghalusan butir. Dari hasil pengamatan didapatkan bahwa ukuran butir akan menjadi semakin halus dengan semakin banyaknya passing pada spesimen. Ukuran diameter rata-rata butir pada spesimen pra-ECAP adalah 18 μm, ukuran diameter rata-rata butir pada spesimen ECAP pass pertama, pass kedua, dan pass ketiga yaitu 12 μm, 8 μm¸dan 6 μm, secara berurutan. Selanjutnya diuji kekerasan untuk mengetahui pengaruh proses ECAP pada tiap lewatan. Nilai kekerasan rata-rata untuk spesimen pra-ECAP sebesar 73 HV. Pada pass pertama nilai kekerasan rata-rata sebesar 190 HV untuk penampang membujur dan 194 HV untuk penampang melintang. Pada pass kedua nilai kekerasan sebesar 220 HV untuk penampang membujur dan 213 HV untuk penampang melintang. Sedangkan pada pass ketiga nilai kekerasan sebesar 234 HV untuk penampang membujur dan 235 HV untuk penampang melintang.

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ABSTRACT
In this study, SPD (Severe Plastic Deformation) has been done by ECAP (Equal Channel Angular Pressing) technique using 90° angle on the material Cu-30%Zn. ECAP processing is performed by inserting material into dies, afterwards pressure is given through 40 tons capacity hydraulic compaction machine. ECAP specimens are processed 1 to 3 passing by Bc route. Microstructural observations is performed to determine grain size and grain refining. From the observation, it is found that the grain size will become more refined with increasing number of passing on the specimen. Average grain size for specimen pra-ECAP is 18 μm. Average grain size for specimen ECAP first pass, second pass, and third pass are 12 μm, 8 μm, and 6 μm, respectively. Furthermore, hardness is tested to obtain the effect of ECAP processing trough passing. The average hardness values for specimens pre-ECAP is 73 HV. On the first pass an average hardness value is 190 HV for longitudinal cross sections and 194 HV for transversal cross sections. On the second pass an average hardness value is 220 HV for longitudinal cross sections and 213 HV for transversal cross sections. While on the third pass an average hardness value is 234 HV for longitudinal cross sections and 235 HV for transversal cross sections.