Judul: Studi Literatur Optimasi Pra-Perlakuan Proses Electroless Nickel Plating pada Permukaan Logam Baja
Abstrak: Proses pra-perlakuan merupakan salah satu langkah yang penting dalam electroless nickel plating (EN). Pra-perlakuan dilakukan untuk menghilangkan kontaminan seperti minyak, karat dan pengotor lainya yang dapat menghambat proses adhesi (daya rekat). Studi literatur ini bertujuan menganalisis pra-perlakuan dengan berbagai parameter yang berbeda untuk mengetahui pra-perlakuan yang paling optimal pada permukaan substrat baja dengan proses EN. Optimasi praperlakuan EN yang dilakukan pada baja karbon rendah AISI 1040 dengan metode Taguchi menunjukkan bahwa perbedaan pra-perlakuan akan mempengaruhi hasil EN. Perlakuan mekanis dengan sandblasting tidak direkomendasikan sedangkan pengamplasan dan aktivasi dengan asam kuat pada substrat akan menambah kemampuan deposisi pelapis Ni-P.
Keyword: Baja Karbon, Electroless Nickel plating, optimasi, pra-perlakuan

Judul: The Optimization of Temperature and Voltage on  Thickness, Hardness, and Corrosion Rate of Hard Chrome Plating
Abstrak: Baja karbon AISI 1045 merupakan jenis baja karbon sedang yang banyak dimanfaatkan diberbagai bidang. Namun, kerentanan sifat logam terhadap korosi mendorong peningkatan kualitas sifat logam. Pelapisan hard chrome merupakan salah satu teknik perlindungan material yang memiliki banyak keunggulan. Selain memberikan perlindungan korosi, pelapisan hard chrome meningkatkan sifat kekerasan material yang berdampak pada meningkatnya ketahanan aus material. Tujuan penelitian ini adalah menentukan kondisi optimum suhu dan tegangan dalam proses pelapisan hard chrome terhadap kekerasan, ketebalan dan laju korosi sampel baja karbon AISI 1045. Pelapisan dilakukan dalam larutan hard chrome dengan kadar CrO3 282,56 g/L dengan ragam suhu, yaitu 45, 55, dan 65 °C serta ragam tegangan 6, 8, dan 12 V. Berdasarkan hasil pengamatan secara visual dan kuantitatif, kondisi optimum diperoleh pada suhu 55 °C tegangan 8 V dengan ketebalan 0,0041 cm, kekerasan 37 HRC, dan laju korosi 0,0412 mm/tahun., AISI 1045 carbon steel is medium carbon steel widely used in various fields. However, the metal susceptibility to corrosion encourages the increase in metal quality. Hard chrome plating is one of the material protection techniques which has a lot of advantages. It does not only protect against corrosion, but it also increases the hardness of material increase of material wear resistance. The study aimed to determine the optimum conditions of temperature and voltage in the hard chrome plating process on thickness, hardness, and corrosion rate of AISI 1045 carbon steel. The plating was conducted in a hard chrome solution containing CrO3 282,56 g/L with temperature variations of 45, 55, and 65 °C as well as voltage variations of 6, 8, and 12V. The result of visual and quantitative observation indicated that the optimum plating condition is obtained at a temperature of 55 °C voltage 8 V with a thickness of 0,0041 cm, hardness of 37 HRC, as well corrosion rate of 0,0412 mm/year.
Keyword: carbon steel 1045, hard chrome plating, optimum condition

Judul: Thermal Characteristics and Dynamics of Tropical Cyclone over Western North Pacific Ocean: A Case Study of Typhoon Songda (Chedeng) 2011
Abstrak: The frequent occasion of Tropical Cyclone (TC) over Western North Pacific (WNP) Ocean lies from 10˚N to 26˚N and 121˚E to 170˚E. Sources of TC development come from warm ocean temperature where latent heat is released during condensation processes and subsequently concentrated in the boundary layer. Relative humidity at 850-700 hPa is responsible to produce the most intense storm. Meanwhile, weak vertical wind shear between 850-200 hPa is one of the dynamical factors that lead to the development of TC. Pressure level of 850-200 hPa is chosen to minimize the thermodynamic effect in the lower troposphere. Typhoon Songda (Chedeng in the Philippines) or TSC lasted from May 18th to 30th, 2011 and strengthened into powerful Super Typhoon stage between May 24th and 27th. Long curving track and the exhibition of all sequences of TC life cycle, TSC is then considered as an ideal case of TC. The objective of the study with case of TSC is to investigate the role of thermal characteristics and dynamics on TC intensity. The research is carried out by using Advanced Research of Weather Research and Forecasting model (WRF ARW model) version 3.3. Two domains are employed in the model. The first domain situate from 02˚N to 40˚N and 118˚E to 149˚E and cover spatial resolution () of 33.1 km. The second domain situate from 09˚N to 27˚N and 119˚E to 132˚E with of 11 km. Timestep of the model () is 120 seconds. The model is supported by the following physical parameterization, i.e., Yonsei University Scheme (YSU) in the boundary layer, Kain-Fritsch scheme (KF) in the cumulus, and WRF Single-Moment 3-class scheme in the microphysics. Initial meteorological condition prior to the formation of the cyclone is generated using WRF ARW standard-release model. Sensitivity of the model output is obtained from a selected single-parameter change scenarios, namely, 10 % to 20 % decrease and increase of wind shear initial data at 850-200 hPa, and by 10 % to 20 % decrease of relative humidity initial data at 850-700 hPa. The result showed that the negative correlations between wind shear and intensity are found in wind shear scenarios. Wind shears of 10 ms-1 which lead to strengthening of the wind intensity in the early period of Typhoon development are found in wind shear scenarios. The effect of wind shear changes on wind intensity is statistically significant in the 20 % wind shear scenarios. During mature stage, weak wind intensity occurred when wind shear increase as given in the WRF standard-release and the 20 % decreasing scenario. Different situation is found in the 20 % increasing scenario where wind shear tend to weak and lead to strong wind intensity at this stage. Meanwhile, the reduction of moisture supply at 850-700 hPa resulting from 20 % decreasing relative humidity play a major role in the weakening of wind intensity and reduces mechanical energy of the cycle process as much as 300 J kg-1.
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