Hasil Pencarian  ::  Simpan CSV :: Kembali

Abstrak :
Proses pengerasan permukaan pada dies stamping dengan metode nitriding dilakukan untuk meminimalisir efek gesekan yang ditimbulkan. Powder nitriding merupakan salah satu metode nitriding dengan biaya investasi dan proses yang relatif lebih rendah dibandingkan dengan metode gas dan plasma. Pupuk urea sebagai alternatif sumber nitrogen yang memiliki konsentrasi nitrogen minimum 46% yang terdekomposisi sempurna menjadi gas amonia dan kemudian terdisosiasi menjadi nitrogen dalam bentuk mono atomik pada temperatur 500º-600ºC. Percobaan proses powder nitriding dilakukan pada baja AISI H13 yang sebelumnya telah dikeraskan didalam vacuum furnace dengan quenching gas nitrogen dengan tekanan 1.9 bar. Pada percobaan powder nitriding dilakukan variasi temperatur 500ºC, 550ºC dan 600ºC dengan waktu proses 2 jam, 4 jam dan 6 jam serta variasi konsentrasi nitrogen dalam jumlah urea 200 gram, 300 gram dan 400 gram yang kemudian dikarakterisasi dengan micro hardenss test, pengamatan struktur mikro dengan menggunakan microscope optic dan scanning electron microscope serta energy dispersive X-ray spectroscopy. Hasil pengujian sifat mekanik menunjukkan nilai uji kekerasan akan semakin meningkat seiring dengan peningkatan temperatur, konsentrasi nitrogen dan waktu proses. Pengamatan struktur mikro membuktikan bahwa kedalaman zona difusi dipengaruhi oleh parameter proses yang berkorelasi dengan hasil uji kekerasan. Selain itu, hasil karakterisasi energy dispersive X-ray spectroscopy pada compound layer merupakan area yang memiliki konsentrasi nitrogen paling tinggi dan kemudian konsentrasi nitrogen menurun pada zona difusi. Fasa tunggal epsilon dengan konsentrasi nitrogen paling tinggi yaitu 28,69 at% diperoleh pada parameter temperatur 600ºC pada waktu proses 6 jam dan jumlah urea 400 gram yang juga merupakan parameter optimum yang memiliki nilai kekerasan yang paling tinggi dan kedalaman difusi yang paling dalam. Kesimpulan menunjukkan bahwa parmeter temperatur, waktu dan konsentrasi nitrogen memiliki keterkaitan yang berpengaruh terhadap pembentukkan presipitat nitrida yang berperan dalam peningkatan kekerasan permukaan. ......The process of surface hardening on dies stamping using the nitriding method is carried out to minimize the friction effect. Powder nitriding is a nitriding method with a relatively lower investment and process cost compared to the gas and plasma methods. Urea fertilizer as an alternative source of nitrogen which has a minimum nitrogen content of 46% which is completely decomposed into ammonia gas and then dissociates into nitrogen mono-atomic at a temperature of 500º-600ºC. The powder nitriding process experiment was performed on AISI H13 steel which was previously hardened in a vacuum furnace with quenching nitrogen gas with a pressure of 1.9 bar. in the powder nitriding experiment, temperature variations were carried out at 500ºC, 550ºC and 600ºC with a processing time of 2 hours, 4 hours and 6 hours and variations in nitrogen concentration in the amount of urea 200 grams, 300 grams and 400 grams in the powder nitriding process for AISI H13 steel, characterized by micro hardenss test, observation micro structure using a microscope optic and scanning electron microscope as well as energy dispersive X-ray spectroscopy. The results of the mechanical properties examination indicated the hardness test will increase with increasing temperature, nitrogen concentration and processing time. Microstructure observations prove that the depth of the diffusion zone is influenced by process parameters which correlate with the hardness test results. In addition, the result of energy dispersive X-ray spectroscopy on the compound layer is the area that has the highest nitrogen concentration and then the nitrogen concentration decreases in the diffusion zone. The single-phase epsilon with the highest nitrogen concentration of 28.69 at% was obtained at a temperature parameter of 600ºC at 6 hours processing time and the amount of urea 400 grams which is also the optimum parameter which has the highest hardness value and the deepest diffusion depth. The conclusion shows that the parameters of temperature, time and nitrogen concentration have a relationship that affects the formation of nitride precipitates which play a role in increasing surface hardness.

Abstrak :
ABSTRACT
High carbon steel generally has a high hardness but lower ductility. To obtain a hard and ductile material, surface hardening can be done on a low carbon steel. Surface hardening can be achieved by hard chrome plating. The objectives of this research were: (1) Conducting the process of hard chrome plating on low carbon steel, (2) Knowing the increasing of surface hardness of low-carbon steel after the plating process in time variations, (3) Knowing the increasing of surface hardness of the low carbon steel after the coating process in anode-cathode distance variations. The specimens was made of low carbon steel. The size of the specimen were 40 mm in length, 35 mm in width and 6.8 mm in thickness. The variables measured were: (1) Coating time (t), (2) The distance between the cathode and anode in the coating process (l). After the coating process completed, the specimen surface hardness was measured by Vickers Hardness Tester. The results showed that up to 532 HV, low carbon steel hardness increased linearly at increasing time plating. At 120 minutes plating, the hardness also increased linearly at current densities up to 1.05 amperes/dm2. While at the current density of 1.1 amperes/dm2, the hardness increased significantly higher.

Abstrak :
Stainless steel memiliki struktur mikro yang lengkap dan stabil dan banyak digunakan dalam industri modern seperti pembuatan kapal uap, produksi kimia dan reaktor nuklir karena ketahanan terhadap korosi dan kemampuan mekanik yang baik terhadap suhu tinggi, perlakuan panas tidak akan mempengaruhi kekerasan permukaan, perlu ditempa untuk mengurangi ukuran butir sehingga dapat mengeraskan permukaan menggunakan variasi beban 1 kg, 2 kg, 3 kg, mengkarakterisasi bahan menggunakan teknik difraksi sinar-X (XRD), dan sifat elektrokimia menggunakan teknik Linear Sweep Voltammetry (LSV), Open Circuit Potentiometry Technique (OCP) dan Cyclic Voltammetry (CV) dalam NaCl 3,5% wt. Terdapat pengecilan ukuran bulir pada sampel yang telah di beri penempaan dari 21 nm menjadi 10 nm pada 1 kg, 34 nm pada 2 kg, 10 nm pada 3 kg dan 4 nm pada 4 kg, karena penempaan juga menambah banyak nya grain menyebabkan potensi korosi semakin timggi yaitu laju korosi pada sampel dari 1,45 μm/tahun, menjadi 1,19 μm/tahun pada 1 kg, 1, 91 μm/tahun pada 2 kg dan 2,62 μm/tahun pada 3 kg dengan suhu uji 25 ̊C menggunakan larutan NaCl 3,5% wt......Stainless steel has a complete and stable microstructure and is widely used in modern industries such as steamship making, chemical production, and nuclear reactors because of its corrosion resistance and good mechanical ability to high temperature, heat treatment will not affect the surface hardness, need to be forged to reduce grain size so that it can harden the surface using variations in the load of 1 kg, 2 kg, and 3 kg, characterize material using X-ray diffraction technique, and the electrochemical properties using linear sweep voltammetry technique (LSV), open circuit potentiometry technique (OCP) and Cyclic Voltammetry (CV) in NaCl 3.5% wt. There is a reduction in grain size in the sample which has been forged from 21 nm to 10 nm at 1 kg, 34 nm at 2 kg, 10 nm at 3 kg and 4 nm at 4 kg because forging also adds much grain causing more corrosion potential lead is the corrosion rate in the sample from 1.45 μm / year, to 1.19 μm / year at 1 kg, 1, 91 μm / year at 2 kg and 2.62 μm / year at 3 kg with a test temperature of 25 ̊C using a solution of NaCl 3.5% wt