Hasil Pencarian  ::  Simpan CSV :: Kembali

"?Chemical engineers designing, operating and maintaining their ever-expanding industry during the second half of the 20th century relied heavily on stainless steels. Few, however, were familiar with or understood its history. This treatise satisfies that shortcoming in an interesting, readable manner. The ?Timeline? alone is a remarkable presentation.? Richard Leonard, retired, Hercules, Inc."

"ABSTRAKPendahuluan: Braket ortodonti merupakan komponen penting dalam pirantiortodonti cekat karena menghantarkan gaya dari kawat ke struktur gigi dan jaringanpendukungnya sehingga terjadi pergerakkan gigi. Komposisi logam dan prosesmanufaktur braket Stainless Steel mempengaruhi sifat fisik dan mekanis, salahsatunya kekerasan dan kekuatan. Tetapi, beberapa pabrik mengurangi biaya produksidengan mengabaikan proses manufaktur yang sesuai dengan standarisasi. Hal inidapat menyebabkan deformasi slot braket khususnya saat diaplikasikan gaya torque.Deformasi slot braket dapat mengurangi besar gaya torque yang akan dihantarkan kegigi dan jaringan pendukungnya sehingga hasil perawatan tidak efektif dan efisien.Beberapa braket Stainless Steel yang beredar dipasaran masih diragukan kualitasnyadalam perawatan ortodonti.Tujuan: Untuk membandingkan besar gaya torque akibat sudut puntir 300dan 450kawat Stainless Steel serta deformasi slot permanen akibat gaya torque tersebut antarakelompok merk braket (3M, Biom, Versadent, Ormco dan Shinye).Metode Penelitiian: Lima puluh braket Stainless Steel edgewise dari 5 kelompokmerk braket (n=10) di lem ke akrilik. Masing-masing braket dilakukan pengukurantinggi slot dengan mikroskop stereoskopi, lalu diaplikasikan puntiran kawat melaluialat yang sudah dibuat pada penelitian ini sehingga diperoleh besar gaya torque.Setelah uji torque, dilakukan kembali pengukuran tinggi slot braket. Deformasi slotpemanen dihitung dari selisih dua tahapan pengukuran tinggi slot yaitu sebelum dansesudah aplikasi gaya torqueHasil: Analisis statistik menunjukkan perbedaan bermakna besar gaya torque padasudut puntir 300 dan 450 antara Biom dan Shinye dengan Omrco. Gaya torque palingbesar yaitu pada merk braket 3M (300= 442,12 gmcm dan 450= 567,99 gmcm) ,sedangkan yang terkecil adalah Biom (300= 285,50 gmcm, 450=361,38 gmcm).Perbedaan deformasi slot braket terjadi hampir pada semua kelompok merk braket.Deformasi slot braket hanya terjadi pada merk braket Biom (2,82 µm) dan Shinye(2,52 µm).Kesimpulan: Bentuk geometri slot, komposisi, proses manufaktur braket StainlessSteel dan sudut puntir kawat mempengaruhi besar gaya torque. Komposisi AISI 303dan 17-4 PH serta proses manufaktur melalui MIM menghasilkan deformasi slotbraket yang kecil dan secara klinis tidak signifikan.

---

ABSTRACTIntroduction: Orthodontic bracket is an important component in fixed orthodonticappliances for distributing force to the structure of the tooth and its supportingtissues, causing tooth movement. Alloy composition and manufacturing processStainless Steel bracket affects the physical and mechanical properties, one of whichhardness and strength. However, some manufacturers reduce costs at themanufacturing process in accordance with standards. This can cause deformation ofthe bracket slot especially when applied torque force. In addition, slot deformationcan reduce the torque force that will be transmitted to the tooth and its supportingtissues so that the treatment is ineffective and inefficient. Therefore, some StainlessSteel brackets quality in the market is still questionable for orthodontic treatments.Objective: To determine the deformation of the bracket slot of five brands (3M,Biom, Versadent, Ormco and Shinye) due to the force Stainless Steel wire withtorsional angle of 45° and the amount of torque force with torsional angle of 30° and45°.Methods: Fifty Stainless Steel Edgewise brackets from five bracket groups brands (n= 10) is attached onto an acrylic. Each bracket slot height was measured with amicroscope stereoscopy, then applied torsion wire through torque apparatus that hasbeen made for this study to obtain the amount of torque force. Once the torque testhas been done, then the width of bracket slot is re-measured. Deformation slotcalculated from measurements of height difference between before and after thetorque test.Results: Statistical analysis shows differences in slot bracket deformation in all groupof bracket brands. But, clinically permanent slot deformation deformation occurs onlyon Biom (2.82 µm) and Shinye (2.52 µm). Repeated measure ANOVA comparisonshowed significant differences in the amount of torque at torsion angle of 300 and 450between Biom and Shinye with Omrco. The 3M transmitted highest load (300 =442,12 gmcm and 450 = 567,99 gmcm), while the lowest is Biom (300 = 285,50gmcm and 450 = 361,38 gmcm).Conclusion: Stainless Steel bracket slot deformation is influenced by several factorsspecifically geometry bracket slot, the composition of the metal, manufacture andtorsional angle wire. Alloy composition of AISI 303 and 17-4 PH and manufacture bythe method of metal injection molding (MIM) has the smallest deformation."

"ABSTRAKTiN material yang popular sebagai protective coating pada tools karena mempunyai hardness sekitar 2200 VHN. Pelapisannya pada Stainless steel kami lakukan dengan metoda sputtering reaktif dimana selain gas Argon sebagai gas sputter juga diniasukkan gas Nitrogen yang diharapkan bereaksi Nitridasi dengan atom atom tersputter Titanium menjadi Titanium Nitrida pada substrat yang dipanaskan. Pada penelitian tahap kedua ini dibuat beberapa sampel Stainless Steel dilapisi lapisan tipis TiN Titanium Nitrida secara sputtering reaktitf dengan menggunakan modifikasi pada Universal Coating Machine Leybold Haeraus UNIVEX 300. Dengan menggunakan modifikasi geometris lingkungan terbatas dan penyempumaan sistim pemanasan sampel dihasilkan beberapa sampel yang baik. Secara umum peningkatan kekerasan melebih 200persen max. 669persen pada Stainless Steel; yang mana jauh lebih baik dari hasil penelitian Tahap I yang hanya menghasilkan peningkatan maksimum 95persen. Demikian pula hasil-hasil ini jauh lebih reprodusibel dibandingkan dengan hasil penelitian Tahap I hampir semua sampel jadi. Karakterisasipun telah bertambah dengan XRD dengan hasil yang memuaskan. Sekalipun demikian dijumpai kendala-kendala baru yang semakin menantang: 1 Daya lekat beberapa sampel tidak baik mengelupas. 2. Pemanasan hanya mencapai 300 C dan berefek samping kerusakan beberapa komponen penting sistim vakum. 3. Flowmeter gas kurang peka kalanya. Ini semua akan diupayakan jalan pemecahannya pada penelitian Tahap III yang akan di titik beratkan pada penyempumaan teknik fabrikasi dan solusi kendala kendala tersebut. Demikian pula akan ditambahkan karakterisasi dengan SEM."

"An investigation to structural and wear behaviour of nitrided AISI 316 L stainless steel resulting from low temperature fluidized bed nitriding has been made in the present work It was found that the wear resistance of nitrided specimens was related to the formation of a preetpitation-free hardened layer on the austenitic surface. In the present laboratory experiments, the precipitation-free or S phase layer with a surface hardness of ~1350 H Va 5 was produced at a nitriding condition of 450'C for 6h. The formation of this S phase layer significantly improved wear resistance of the stainless steel. Wear track observation by SEM revealed that the specimens without formation of S phase layer produced heavy scars due to tearing and local plastic deformation. The present work also suggests that fluidized bed heat treatment furnace can be utilised for nitriding the austenitic stainless steels at low temperatures below 5 00 ?C to produce S' phase nitrdid layer without losing the stainless feature of this material."

"Dalam satu sistem reactor nuklir yang meliputi bejana tekn, penyangga komponen-komponen utama, pemipaan sistem pendingin serta selongsong bahan bakar, mempunyai persyaratan-persyaratan material yang berlainan dan berbada sesuai dengan tipe reactor. Secara khusus persyaratan material reactor daya tersebut meliputu syarat fisik atau mekanik dan persyaratan nuklir material. Stainless steel merupakan baja tahan karat otentik, yang terdiri dari paduan logam Fe, Cr, dan Ni yang memberikan sifat mekanik yang baik dan ketahanan terhadap korosi pada temperature tinggi."

"The 56Fe16.6Cr25Ni0.9Si0.5Mn austenitic superalloy has been produced in an induction furnace; it was made from granular ferro-scrap, ferrochrome, ferrosilicon, and ferromanganese materials. Originally, this alloy had been proposed for use in high mechanical loads and high temperature conditions (such as in nuclear and fossil fuel power plant facilities). Tensile strength tests showed that the alloy has an average yield strength of about 430.56 MPa, which is higher than Incoloy A-286 (a commercially available alloy). A combination of microscopy techniques by means of an optical microscope, X-ray diffraction [XRD], scanning electron microscopy [SEM], and transmission electron microscopy [TEM] techniques were applied in order to get detailed information about the fine structure of the alloy. XRD confirmed that the alloy matrix exhibits an FCC crystal structure with a lattice parameter of about 3.60 Å and grain sizes ranging from 50 to 100 µm. The results of the TEM analysis revealed the new type of precipitations that formed at the grain boundaries. These needle-like precipitations, probably Fe/Cr-rich precipitations of the (Fe,Cr)xCy type, acted as the source of intergranular corrosion (IGC). Small coherent plate-like and much smaller granular precipitations were found distributed homogenously along grain boundaries and inside the grains. Combining the tensile strength test and microstructure analysis suggested that these precipitations play significant roles in the hardness of the investigated sample."

"Stainless steel 316L dikenal sebagai salah satu material yang paling resistan terhadap korosi pada berbagai macam lingkungan. Ketahanan korosi ini disebabkan oleh lapisan tipis kromium yang terbentuk dan melapisi permukaan material secara spontan. Pada penelitian ini, stainless steel 316L mengalami perlakuan panas anil pada suhu 1000°C dengan empat variasi durasi waktu yaitu 0,5 jam, 1 jam, 1,5 jam, dan 2 jam, serta media pendinginan cepat yang digunakan yaitu air. Dari pola difraksi sinar-X diketahui bahwa ukuran kristal fasa austenitik mengalami perubahan yang tidak stabil karena material berada pada proses rekristalisasi dimana ukuran kristal tidak stabil sebelum kemudian berada pada fase grain-growth dimana ukuran kristal akan membesar. Pengamatan korosi dilakukan menggunakan metode voltametri linear (LSV) pada larutan 5 x M dengan pH = 2. Data yang sudah didapatkan akhirnya diolah menggunakan rumus laju korosi dan didapatkan hasil nilai laju korosi yang berubah-ubah sehingga tidak teramati pola peningkatan atau penurunan, namun nilai laju korosi paling kecil didapatkan pada sampel yang dianil pada durasi waktu terlama yaitu 2 jam.

---

Stainless Steel 316L is recognized as one of the most corrosion-resistant materials in a wide variety of environments. This corrosion resistance is caused by a thin layer of chromium that forms and coats the surface of the material spontaneously. In this study, 316L stainless steel underwent annealing heat treatment at 1000 ° C with four variations of time duration, namely 0.5 hours, 1 hour, 1.5 hours, and 2 hours, and the fast cooling medium used was water. From the X-ray diffraction pattern, it is known that the crystallite size of the austenitic phase experiences an unstable change because the material is in the recrystallization process where the crystal size is unstable before then going into the grain-growth phase where the crystal size will increase. Corrosion observations were carried out using the linear voltammetry (LSV) method in a solution of 5 x M with pH = 2.The data that has been obtained is finally processed using the corrosion rate formula and the results of the corrosion rate change change so that no pattern of increase or decrease is observed, but the smallest corrosion rate value is obtained in the samples annealed for the longest time duration of 2 hours."