Rabu, 19 Oktober 2011
SOAL_SOAL UJIAN SD,SMP,SMA
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Minggu, 19 Desember 2010
Industri Otomotif Nasional
Ancaman ketersediaan minyak bumi serta isu pemanasan global merupakan dua hal terpenting yang mempengaruhi kebijakan industri otomotif dunia saat ini. Hemat energi dan ramah lingkungan menjadi standard utama bagi kendaraan, terutama di negara maju. Guna mengantisipasi tuntutan tersebut, raksasa otomotif seperti Toyota memilih strategi diversifikasi produk (Coup, 1999). Strategi semacam ini cukup tepat mengingat belum matangnya sumber energi selain minyak bumi yang berkorelasi pada masih mahalnya sumber-sumber energi baru tersebut.
Strategi industri otomotif dunia dalam mengantisipasi tuntutan mutakhir tersebut umumnya bermuara pada tiga hal: (1) Perbaikan efisiensi dan karakteristik mesin pembakaran dalam (Internal Combustion Engine-ICE) yang sudah ada saat ini, (2) Kombinasi, baik antar berbagai sumber energi, seperti bensin-bioethanol, solar-biofuel, dan sebagainya, maupun antar teknologi energi, seperti ICE konvensional dengan motor elektrik, (3) Penggunaan sumber dan teknologi energi baru, seperti fuel cell vehicleberbahan bakar hidrogen.
Kecenderungan lain sektor otomotif dunia adalah penyebaran divisi manufaktur dan perakitan di berbagai negara yang besar jumlah penduduknya serta memiliki pertumbuhan ekonomi yang signifikan. Langkah ini awalnya muncul karena regulasi negara-negara yang menjadi sasaran industri otomotif dunia (seperti ketentuan Local Content Requirements-LCRs, dan sebagainya), namun belakangan, usaha untuk menekan biaya produksi menjadi motif utama pendirian divisi manufaktur dan perakitan tersebut (Ivarsson, 2005).(read more,...)
Strategi industri otomotif dunia dalam mengantisipasi tuntutan mutakhir tersebut umumnya bermuara pada tiga hal: (1) Perbaikan efisiensi dan karakteristik mesin pembakaran dalam (Internal Combustion Engine-ICE) yang sudah ada saat ini, (2) Kombinasi, baik antar berbagai sumber energi, seperti bensin-bioethanol, solar-biofuel, dan sebagainya, maupun antar teknologi energi, seperti ICE konvensional dengan motor elektrik, (3) Penggunaan sumber dan teknologi energi baru, seperti fuel cell vehicleberbahan bakar hidrogen.
Kecenderungan lain sektor otomotif dunia adalah penyebaran divisi manufaktur dan perakitan di berbagai negara yang besar jumlah penduduknya serta memiliki pertumbuhan ekonomi yang signifikan. Langkah ini awalnya muncul karena regulasi negara-negara yang menjadi sasaran industri otomotif dunia (seperti ketentuan Local Content Requirements-LCRs, dan sebagainya), namun belakangan, usaha untuk menekan biaya produksi menjadi motif utama pendirian divisi manufaktur dan perakitan tersebut (Ivarsson, 2005).(read more,...)
Minggu, 21 November 2010
Metalografi
Definition Metallography
Micro-analysis is an analysis of the metal structure through enlargement by using a special microscope metallography. With the micro-structure analysis, we can observe the shape and size of metal crystals, damage due to metal deformation process, heat treatment process, and differences in composition.The properties of metals, especially mechanical properties and technological properties highly influenced by the micro-structure of metals and alloys, in addition to their chemical composition. Microstructure of metals can be modified by heat treatment or by the process of changing shape (deformation) of the metal to be tested.
Experiment Process Metallography
Before conducting the experiment metallography of a material, we must first determine what the metal material which we will test. We recommend that there should be a comparison of data between data structures in micro to micro data from the experiment with actual structure of a material that we make the test object.
The steps we have to do in this metallographic experiments are as follows:
1. Cutting (Cutting)
Selection of an appropriate sample from a microscopic study of specimens is very important. The sample selection was based on objective observation was to be done. In general, commercial material is not homogeneous, so that one sample taken from a large volume can not be considered representative. Sampling should be planned so that the produce samples according to the average condition of material or conditions in certain places (critical), also taking into account the ease of cutting. Broadly speaking, sampling conducted in the area to be observed microstructures and makrostrukturnya. For example, for observation of microstructure of materials that have failed, then the samples were taken as close as possible to the area of failure (on the critical areas in the worst condition), and then compared with samples taken from areas far from the area failed. It should be noted also that in the process of cutting, have prevented the possibility of deformation and excessive heat. Therefore, each cutting process must be given adequate cooling.
There are some sample cutting system based on cutting media used, which includes the process of fracture, cutting, sawing, cutting abrasion (abrasive cutter), wire saws, and EDM (Electric Discharge Machining). Based on the resulting rate of deformation, cutting techniques are divided into two, namely:
1. Mechanical cutting with large deformation, using a grinder.
2. Mechanical cutting with small deformation, using a low-speed diamond saw
2. Mounting
Specimens are small or have irregular shapes that would be difficult to handle especially when done sanding and final polishing. An example is a specimen in the form of wire, thin metal sheet specimens, thin pieces, etc.. To facilitate handling, then the specimens should be placed on a medium (mounting media). In general, the conditions that must be owned by the mounting material are:
* Is inert (does not react with the material or substance etching)
* The nature low eksoterimis
* Low Viscosity
* Depreciation of linear low
* Good adhesion properties
* Has the same violence with sample
* Good flowability, can penetrate the pores, cracks and other forms of irregularities found in samples
* Special for electrolytic etching and SEM examination, mounting materials must be conducive
Mounting media should be selected according to the material and type of etching reagent to be used. In general, the mounting use of synthetic plastic material. Can be a resin material (castable resin) is mixed with hardener, or bakelite. The use of castable resins easier and simpler tool used than bakelite, because it is not required the application of heat and pressure. However, this resin castable material does not have good mechanical properties (soft) so that less suitable for hard materials. Mounting technique is best to use a thermosetting resin using bakelite material. This material is a powder that is available with a variety of colors. Thermosetting mounting requires a special tool, because it takes pressure applications (4200 lb/in2) and hot (1490C) in the mold when mounting.
3. Grinding (Sanding)
Freshly cut samples, or samples that have been corroded to have a rough surface. This rough surface structure must be flattened for easy observation to be done. Sanding is done by using a sandpaper abrasive grain size expressed by mesh. The sequence of sanding should be done from a low mesh numbers (up to 150 mesh) to a high mesh number (180 to 600 mesh). The first grit size used depends on surface roughness and depth of the damage caused by cutting.
It should be noted at the time of sanding is the provision of water. Water serves as pemidah growled, minimize heat damage arising that can alter the microstructure of the samples and extend the use of sandpaper. Another thing to note is that when altering the direction of sanding, the new direction is 450 or 900 of the previous direction.
4. Polishing (polishing)
Once sanded until smooth (600 #), the sample must be done polishing. Polishing aims to obtain a smooth sample surface free of scratches and shiny like a mirror and eliminate irregularities to the order of 0:01 μm sample. Surface samples will be observed under the microscope must be absolutely flat. If the sample surface rough or bumpy, the observation of micro structure will be difficult to do because the light coming from the microscope were randomly reflected by the surface samples.
Polishing stage begins with a coarse polishing first and then proceed with fine polishing. There are 3 methods of polishing, among others, are as follows:
a. Electrolyte Chemical polishing
Current density and voltage relationship varies to a solution of electrolytes and different materials in which to stress, a thin layer formed on the surface, and almost no current passing, the etching process occurs. While in high voltage occurs polishing process.
b. Chemical mechanical polishing
Is a combination of etching and chemical mechanical polishing carried out simultaneously on a smooth plate. Polishing abrasive particles are mixed with a solution commonly used etcher.
c. Electro Mechanical polishing (Method Reinacher)
Is a combination of electrolytic and mechanical polishing on the polishing plate. This method is very good for precious metals, copper, brass, and bronze.
5. Etching (Etching)
Etching is the process of grain boundary attack or erosion are selectively and controlled by immersion into the solution etcher using either electricity or not the sample surface so that the detailed structure will be observed will be seen clearly and sharply. For some materials, a new microstructure appears if given substance etching. So we need the right knowledge to choose the appropriate etching agent.
a. Chemical Etching
Is an etching process using etching chemical solution in which the substance used has its own characteristics so that the election be adjusted with the sample to be observed. Examples include: nitrid acid / nital (nitric acid + alcohol 95%), picral (picric acid + alcohol), ferric chloride, hydroflouric acid, etc.. Keep in mind that not too lam etching time (typically about 40-30 seconds), and after etched, immediately washed with running water and then with alcohol and then dried with a dryer.
b. Electro Etching (electrolytic etching)
Is an etching process using elektoetsa reaction. How this is done by setting the voltage and electrical current strength and time of etching. Etching of this type are usually specialized for stainless steel due to the chemical etching is difficult to obtain detailed structure
Equipment:
Accutom cutting machine with diamond cutting
Abrasive Cutter Buehler Metaserv
Low Speed Ecomet
Herzog Mounting Equipment
Grinding Machine Ecomet 3
Cole Parmer 8850 Ultrasonic washing
Micro-analysis is an analysis of the metal structure through enlargement by using a special microscope metallography. With the micro-structure analysis, we can observe the shape and size of metal crystals, damage due to metal deformation process, heat treatment process, and differences in composition.The properties of metals, especially mechanical properties and technological properties highly influenced by the micro-structure of metals and alloys, in addition to their chemical composition. Microstructure of metals can be modified by heat treatment or by the process of changing shape (deformation) of the metal to be tested.
Experiment Process Metallography
Before conducting the experiment metallography of a material, we must first determine what the metal material which we will test. We recommend that there should be a comparison of data between data structures in micro to micro data from the experiment with actual structure of a material that we make the test object.
The steps we have to do in this metallographic experiments are as follows:
1. Cutting (Cutting)
Selection of an appropriate sample from a microscopic study of specimens is very important. The sample selection was based on objective observation was to be done. In general, commercial material is not homogeneous, so that one sample taken from a large volume can not be considered representative. Sampling should be planned so that the produce samples according to the average condition of material or conditions in certain places (critical), also taking into account the ease of cutting. Broadly speaking, sampling conducted in the area to be observed microstructures and makrostrukturnya. For example, for observation of microstructure of materials that have failed, then the samples were taken as close as possible to the area of failure (on the critical areas in the worst condition), and then compared with samples taken from areas far from the area failed. It should be noted also that in the process of cutting, have prevented the possibility of deformation and excessive heat. Therefore, each cutting process must be given adequate cooling.
There are some sample cutting system based on cutting media used, which includes the process of fracture, cutting, sawing, cutting abrasion (abrasive cutter), wire saws, and EDM (Electric Discharge Machining). Based on the resulting rate of deformation, cutting techniques are divided into two, namely:
1. Mechanical cutting with large deformation, using a grinder.
2. Mechanical cutting with small deformation, using a low-speed diamond saw
2. Mounting
Specimens are small or have irregular shapes that would be difficult to handle especially when done sanding and final polishing. An example is a specimen in the form of wire, thin metal sheet specimens, thin pieces, etc.. To facilitate handling, then the specimens should be placed on a medium (mounting media). In general, the conditions that must be owned by the mounting material are:
* Is inert (does not react with the material or substance etching)
* The nature low eksoterimis
* Low Viscosity
* Depreciation of linear low
* Good adhesion properties
* Has the same violence with sample
* Good flowability, can penetrate the pores, cracks and other forms of irregularities found in samples
* Special for electrolytic etching and SEM examination, mounting materials must be conducive
Mounting media should be selected according to the material and type of etching reagent to be used. In general, the mounting use of synthetic plastic material. Can be a resin material (castable resin) is mixed with hardener, or bakelite. The use of castable resins easier and simpler tool used than bakelite, because it is not required the application of heat and pressure. However, this resin castable material does not have good mechanical properties (soft) so that less suitable for hard materials. Mounting technique is best to use a thermosetting resin using bakelite material. This material is a powder that is available with a variety of colors. Thermosetting mounting requires a special tool, because it takes pressure applications (4200 lb/in2) and hot (1490C) in the mold when mounting.
3. Grinding (Sanding)
Freshly cut samples, or samples that have been corroded to have a rough surface. This rough surface structure must be flattened for easy observation to be done. Sanding is done by using a sandpaper abrasive grain size expressed by mesh. The sequence of sanding should be done from a low mesh numbers (up to 150 mesh) to a high mesh number (180 to 600 mesh). The first grit size used depends on surface roughness and depth of the damage caused by cutting.
It should be noted at the time of sanding is the provision of water. Water serves as pemidah growled, minimize heat damage arising that can alter the microstructure of the samples and extend the use of sandpaper. Another thing to note is that when altering the direction of sanding, the new direction is 450 or 900 of the previous direction.
4. Polishing (polishing)
Once sanded until smooth (600 #), the sample must be done polishing. Polishing aims to obtain a smooth sample surface free of scratches and shiny like a mirror and eliminate irregularities to the order of 0:01 μm sample. Surface samples will be observed under the microscope must be absolutely flat. If the sample surface rough or bumpy, the observation of micro structure will be difficult to do because the light coming from the microscope were randomly reflected by the surface samples.
Polishing stage begins with a coarse polishing first and then proceed with fine polishing. There are 3 methods of polishing, among others, are as follows:
a. Electrolyte Chemical polishing
Current density and voltage relationship varies to a solution of electrolytes and different materials in which to stress, a thin layer formed on the surface, and almost no current passing, the etching process occurs. While in high voltage occurs polishing process.
b. Chemical mechanical polishing
Is a combination of etching and chemical mechanical polishing carried out simultaneously on a smooth plate. Polishing abrasive particles are mixed with a solution commonly used etcher.
c. Electro Mechanical polishing (Method Reinacher)
Is a combination of electrolytic and mechanical polishing on the polishing plate. This method is very good for precious metals, copper, brass, and bronze.
5. Etching (Etching)
Etching is the process of grain boundary attack or erosion are selectively and controlled by immersion into the solution etcher using either electricity or not the sample surface so that the detailed structure will be observed will be seen clearly and sharply. For some materials, a new microstructure appears if given substance etching. So we need the right knowledge to choose the appropriate etching agent.
a. Chemical Etching
Is an etching process using etching chemical solution in which the substance used has its own characteristics so that the election be adjusted with the sample to be observed. Examples include: nitrid acid / nital (nitric acid + alcohol 95%), picral (picric acid + alcohol), ferric chloride, hydroflouric acid, etc.. Keep in mind that not too lam etching time (typically about 40-30 seconds), and after etched, immediately washed with running water and then with alcohol and then dried with a dryer.
b. Electro Etching (electrolytic etching)
Is an etching process using elektoetsa reaction. How this is done by setting the voltage and electrical current strength and time of etching. Etching of this type are usually specialized for stainless steel due to the chemical etching is difficult to obtain detailed structure
Equipment:
Accutom cutting machine with diamond cutting
Abrasive Cutter Buehler Metaserv
Low Speed Ecomet
Herzog Mounting Equipment
Grinding Machine Ecomet 3
Cole Parmer 8850 Ultrasonic washing
Minggu, 14 November 2010
Jumat, 12 November 2010
Aluminium Recycling
Aluminium recycling is the process by which scrap aluminium can be reused in products after its initial production. The process involves simply re-melting the metal, which is far less expensive and energy intensive than creating new aluminium through the electrolysis of aluminium oxide (Al2O3), which must first be mined from bauxite ore and then refined using the Bayer process. Recycling scrap aluminium requires only 5% of the energy used to make new aluminium.[1] For this reason, approximately 31% of all aluminium produced in the United States comes from recycled scrap.[2]http://en.wikipedia.org/wiki/Aluminium_recycling
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