Hasil Pencarian  ::  Simpan CSV :: Kembali

Abstrak :
Penelitian Penelitian kali ini berfokus pada pengaruh unsur logam tanah jarang Cerium Ce terhadap fasa intermetalik yang terbentuk pada saat proses solidifikasi, unsur Cerium yang ditambahkan sebesar 0.1; 0.3 dan 0.5 wt pada matriks Al-5Zn-0.5Cu.Dengan penambahan unsur Cerium Ce semakin banyak, sesuai dengan urutannya, maka anoda korban akan semakin turun efisiensinya. Penambahan unsur Cerium pada proses mempengaruhi Icorr sebagai efisiensi dari anoda korban, yaitu 6.2 x 10-5 , 5 x 10-5 dan 4.57 x 10-5 Volt. Selain itu penambahan Cerium semakin banyak akan membuat ukuran butir semakin kecil, yaitu 167, 133, dan 118 ?m. Fasa intermetalik yang terbentuk dapat dilihat pada grafik grafik hasil pengujian DSC Differential Scanning Calometry dimana grafik tersebut menjelaskan terdapatnya fasa Al11Ce3 Al8Cu4 Ce Al dan Al2Zn2Ce yang dapat mempengaruhi efisiensi anoda korban.

---

The research is focused on the effect of Rare Earth Cerium Ce element on the microstructure morphology during the solidification proccess. The concentration of Cerium Ce addition are 0.1 0.3 0.5 wt on Al 5Zn 0.5Cu matrix and corelated to the characteristic and mechanism of corrosion proccess in Al 5Zn 0.5Cu sacrificial anode. In this research, Aluminium alloy will get the optimum addition if it seen from the microstructure at 0.5 wt addition, but it reverse to the corrosion mechanism on the sacrificial anode. The more and more addition of Cerium, the morphology of microstructure is finer and equixed, but the corrosion rate of the sacrificial anode decrease. The effect of Differential Scanning Calorimetry DSC on the microstructure can be seen on the morphology of the presipitate. With the addition of the element Cerium on the sacrificial anode Al 5Zn 0.5Cu produce phase formed are Al2Zn2Ce , Al8Cu4Ce which may affect the efficiency of the sacrificial anode.

Abstrak :
The directional solidification which is not toward to riser causes the shrinkage defect. This defect can be predicted by investigating the temperature distribution in riser or casting products. The goal of this research is to examine the temperature distribution using Finite Element Software (ANSYS) and then an ad hoc experiment has been performed to verify the result of the simulation, especially the existences cf shrinkage The simulation is carried out by sand casting process using pure aluminum. This research uses enthalpy method to examine the distribution of temperature. The properties of melted metal that being used for the simulation are enthalpy H(T) and thermal conductivity k(T). For experiment, the sand casting process uses pure aluminum and eutectic aluminum. The eutectic aluminum castings is used to support the pure aluminum castings. The result of the simulation hypothesis against shrinkage defect is appropriate with the experiment result.

Abstrak :
A phase field model has been successfully constructed to simulate the behavior of the semi-crystalline polymer solidification phenomenon. It is a model that has been widely and successfully utilized to simulate solidification phenomena in metals. However, the non-conserved phase field equation can be extended to include unique polymer parameters that do not exist in metals; for example, polymer melt viscosity and the diffusion coefficient. In order to extend this model, we incorporate free energy density and non-local free energy density based on the Harrowell-Oxtoby and Ginzburg-Landau theorems for polymer. By using the expansion principle for the higher order of binary phase field parameter, a full modified phase field equation can be obtained. The solidification phenomenon in polymer is very important to optimize the final properties of the products. Here, we use our modified equation to investigate the effect of melting temperature on the rate of solidification. It was found that the rate of solidification is correlated with melting temperature in a non-straightforward manner.

Abstrak :
Pengaruh logam tanah jarang erbium sebagai unsur paduan Al-5Zn-0,5Cu dengan kadar 0wt, 0,1wt, 0,3wt dan 0,5wt diteliti dengan menggunakan OES, DSC, OM, dan polarisasi siklik. OES dilakukan untuk melihat komposisi kimia dari paduan. Pengujian DSC dilakukan untuk mengidentifikasi perubahan fasa dan proses solidifikasi fasa intermetalik.Pengamatan OM dilakukan untuk melihat ukuran butir dan presipitat yang terbentuk. Polarisasi siklik dilakukan untuk mengetahui perilaku korosi dari paduan. Unsur Erbium pada paduan Al-5Zn-0,5Cu-xEr membentuk presipitat yang dapat menghaluskan butir meingkatkan perilaku korosi dari material. Potensial breakdown atau Eb pada paduan cenderung menurun seiring penambahan unsur erbium, potensial breakdown terendah adalah sampel Al-5Zn-0,5Cu-0,3Er sebesar -0.89 V vs Ag/AgCl. Penambahan unsur erbium dengan kadar yang semakin besar semakin menurunkan potensial paduan menjadi semakin anodik sampai dengan -0,78 V vs SCE sehingga masih dalam batas aman untuk memproteksi baja berkekuatan tinggi.

---

The effect of addition of 0wt , 0.1wt, 0.3wt and 0.5wt erbium rare earth on Al 5Zn 0,5Cu alloy was investigated with Optical emission Specstroscopy, Differential Scanning Calorimetry DSC and Cyclic Polarization, complemented with Optical Microscope OM. Observation with OM was coundcuted to see the changes of the grain size and the precipitate formation. DSC was used to identify the phase transformation and solidification process of intermetallic phase. Cyclic polarization was used to know the corrosion characteristics of Al 5Zn 0,5Cu xSm. The presence of erbium formed precipitates on the grain boundary which made finer grain microstructure and enhance activation of corrosion. Breakdown potential tend to decrease as the increase of erbium content the lowest breakdown potential on this study is Al 5Zn 0,5Cu 0,3Er 0.89 V vs Ag AgCl. Addition of erbium accelerate corrosion rate by making the alloy more anodic. Potential coupling with steel structure is 0,78 V vs SCE, still safe to protect High Strength Steel material.

Abstrak :
Pengaruh unsur logam tanah jarang neodimium terhadap paduan Al-5Zn-0,5Cu diteliti dengan pengamatan mikrostruktur menggunakan mikroskop optik, pengujian Differential Scanning Calorimetry DSC, dan polarisasi siklik. Kadar samarium yang digunakan sebagai variabel adalah 0,1wt, 0,3wt, dan 0,5wt. Pengamatan mikrostruktur dilakukan untuk melihat perubahan ukuran SDAS dan pembentukan presipitat. DSC dilakukan untuk mengidentifikasi transformasi fasa dan proses solidifikasi fasa intermetalik. Polarisasi siklik dilakukan untuk mengetahui perilaku korosi anoda korban Al-5Zn-0,5Cu-xNd. Kehadiran unsur neodimium dapat memodifikasi bentuk presipitat pada batas butir dan memperpendek panjang SDAS. Penambahan unsur neodimium ke dalam anoda korban Al-5Zn-0,5Cu dapat menurunkan ketahanan korosi sumuran. Selain itu, penambahan neodimium sebanyak 0,1 wt, 0,3 wt, dan 0,5 wt menurunkan potensial coupling baja dari -0,661 V vs SSC menjadi masing-masing -0,884 V vs SSC, -0,754 vs SSC, dan -0,771 V vs SSC.

---

The effect of addition of neodymium rare earth on Al 5Zn 0.5Cu alloy was investigated with Optical Microscope OM, Differential Scanning Calorimetry DSC, and Cyclic Polarization. The content variable of neodymium tested was 0.1wt, 0.3wt, dan 0.5wt. Observation with OM was conducted to see the changes of the SDAS and the precipitate formation. DSC was used to identify the phase transformation and solidification process of intermetallic phase. Cyclic Polarization was used to know the corrosion characteristics of Al 5Zn 0.5Cu xNd. The presence of neodymium formed precipitates on the grain boundary which made shorter SDAS. Addition of neodymium as alloying element of Al 5Zn 0.5Cu sacrificial anode may decrease pitting corrosion resistance. In addition, 0.1wt , 0.3wt , dan 0.5wt of neodymium in Al 5Zn 0.5Cu decrease the coupling potential of steel from 0,661 V vs SSC to 0,884 V vs SSC, 0,754 V vs SSC, and 0,771 V vs SSC, respectively.

Abstrak :
ABSTRAK
Pengaruh unsur logam tanah jarang samarium terhadap paduan Al-5Zn-0,5Si diteliti dengan pengamatan Optical Microscope OM , Electrochemical Impedance Spectroscopy EIS dan Uji Efisiensi Anoda Korban. Kadar samarium yang diteliti adalah 0,02wt , 0,1wt , 0,3wt dan 0,5wt . Pengamatan OM dilakukan untuk mengetahui morfologi dari presipitat yang terbentuk dan identifikasi kehadiran unsur-unsur yang ada pada permukaan. EIS dilakukan untuk mengetahui mekanisme korosi dari anoda korban dan uji efisiensi dilakukan mengetahui efisiensi kerja anoda korban. Kehadiran unsur samarium membentuk presipitat pada batas butir yang membuat butir-butir pada mikrostruktur menjadi lebih halus. Presipitat yang terbentuk merusak lapisan pasif aluminium pada permukaan paduan dan mempercepat laju korosi dengan membuat paduan menjadi lebih anodik. Hasil dari penelitian menunjukan semakin banyak samarium yang ditambahkan maka efisiensi dari anoda korban akan meningkat dan terjadi penurunan pada penambahan samarium sebesar 0,1wt .

---

ABSTRACT<>br> The effect of rare earth metal element of samarium on Al 5Zn 0,5Si alloy was studied by observation of Optical Microscope OM , Electrochemical Impedance Spectroscopy EIS and Sacrificial Anode Efficiency Test. The samarium levels studied were 0.02wt , 0.1wt , 0.3wt and 0.5wt . Observation with OM was coundcuted to see the changes of the grain size and the precipitate formation. The EIS is performed to determine the corrosion mechanism of the sacrificial anode and the efficiency test is performed to determine the working efficiency of the sacrificial anode. The presence of samarium formed precipitates on the grain boundary which made finer grain microstructure. The formed precipitates impair the aluminium oxide film on the alloy surface and accelerate corrosion rate by making the alloy more anodic. The result show that, with the increasing Sm content in the alloy, the efficiency of sacrificial anode will increase, but it will decrease with addition 0,1wt samarium.