Harjo Seputro

Bio: Harjo Seputro is an academic researcher. The author has contributed to research in topics: Composite number & Bottom ash. The author has an hindex of 2, co-authored 6 publications receiving 7 citations.

Microsructure and Interface Bottom Ash Reinforced Aluminum Metal Matrix Composite

Abstract: Composites are one kind of new materials that continue constantly to develop. As a new composite material, we propose a solution overcoming the limitations of existing material, namely a composite structure consisting of two or more components with different material properties. In this composite, one component acts as reinforcement and the other as binder. They form a structure with combined properties are better than corresponding composite materials demonstrating several advantages such as light weight, strength, good rigidity and low production cost. T6 heat treatment process ensures the dissolving solution treatment in which the specimen heats at a temperature of 580 °C and held for 6 h in state of rapidly cooled specimen with water down to room temperature. Furthermore, we study the process of aging at which the specimen heats again with various temperatures determined for first sampling of nine specimens as a temperature 160 °C during 3, 5, and 7 h. Then second sampling of nine specimens heated under temperature 180 °C during 3, 5, and 7 h, and third nine specimens was at temperature 180 °C during 3, 5, and 7 h, and then slowly cooled to room temperature. From the analysis of the reaction product by EDX testing, the microstructure formed at the interface between matrix and reinforcement before T6 heating and then was treated by the T6 heat treatment at a temperature 200 °C with holding time for 3, 5, and 7 h. The result remained the same, namely a new compound, that is, Al2MgSiO4 formed, moreover formed additional element having different concentrations for various holding time.

Thermal Properties of As-Cast Bottom Ash Reinforced Aluminum Metal Matrix Composite

Abstract: The purpose of this research is to study characteristics of composite Al 6061 + coal ash, namely: thermal conductivity, linear thermal expansion, and melting point, density, porosity and hardness. Before testing, we carried out T6 treatment of material, where the material solution underwent to sintering at 538 °C during 16 h, then quenching, and artificial ageing. We studied the following cases: for temperatures 200, 225, 250 °C and holding times 8, 12, 16 h. The thermal conductivity tests were performed by using DSC (Differential Scanning Calorimetry) and TDA (Thermal Dilatometry Analysis) for linear thermal expansion, for melting point were used trial and error tests, Archimedes principle was used for density test, and hardness testing by Brinell hardness test. In this study, a minimum value of thermal conductivity factor (5.703 W/m K) was obtained at a temperature 200 °C with holding time 8 h, and a maximum value (8.314 W/m K) was obtained at a temperature 225 °C with holding time 12 h. Minimum value of linear thermal expansion (4.6238 × 10−4/°C) was obtained at a temperature 225 °C with holding time 16 h and maximum value (7.7312 × 10−4/°C) was obtained at a temperature 200 °C with holding time 8 h. The result of test melting point is 700–1000 °C, the optimum value of test density is 2.4044 g/cm3 at 250 °C with holding time 8 h. The optimum value of porosity is 2.8876% at 250 °C with 8 h holding time. The higher aging temperature leads to longer holding time for the material during aging, the diffusion which occurs will be greater so the shrinkage will be even bigger causing a reduction in the volume of large pores. The maximum hardness was attained for the sample at 250 °C and holding time 12 h; the minimum hardness was found for the sample at 200 °C, and holding time 8 h.

The Effect of Electroless Plating on Aluminum Metal Matrix Composite Reinforcement Bottom Ash on the Density and Porosity for Propeller Applications

Abstract: The composite is a combination of two or more different materials with condition of the bonding surface between the two materials. One type of composites that attracts a great attention is metal matrix composites (MMC). In this study, we investigated the influence of variations of Mg and temperature of oxidation on the density and porosity of the composite reinforcement. This composite underwent to a process of electroless plating with variations (% by weight) of magnesium (0.005, 0.010, and 0.015%) and variations in temperature oxidation (100, 200 and 300 °C) at hold for 3 h, with following processing the composite by stir casting method. Based on the average chart, we show that increasing the value of (% by weight) of magnesium and oxidation temperature (°C), the density values further decrease. This is caused by the imbalance between the weight of magnesium particles moistened (coal bottom ash) during the electroless plating process. Based on the results of testing, the value of the highest density is achieved at a temperature of 300 °C to oxidation at 0.005% Mg and is equal to 2.609 g/cm3. The value of the lowest density is achieved at a temperature of 200 °C to oxidation at 0.010% Mg and is equal to 2.406 g/cm3.

Intensitas Curah Hujan Memicu Tanah Longsor Dangkal di Desa Wonodadi Kulon

Abstract: . Almost every year during the rainy season, landslides continue to haunt the villagers Wonodadi Kulon Ngadirojo Pacitan. Biggest landslides occurred in the past 2009 years. At least, dozens of houses were severely damaged, at least 13 cows are victims and impaired access road connecting the village to the other. Within four (4) years after the great disaster, there has been no attempt to anticipate or prevent the occurrence of landslides. Wonodadi Kulon village at an altitude of 80-500 meters above sea level to be exact in South Kendeng Mountains about 55 miles from downtown Pacitan. Its area is hilly with a slope of 68 degrees. From the survey conducted disaster seems to be increasingly threatened due to changes in land use that was originally in the form of community forest turned into farmland. Land use as agricultural land utilize a relatively steep slope, so that erosion will often occur in the form of erosion gully and soil mass movement (landslides). Erosion at this next level causing a big impact for environmental damage, such as flash floods. Public knowledge about forest conservation and water resources is still low proven that many people who are looking for firewood in the forest. Data from the local village administration mentioned critical land area of 102 hectares land area of 309.30 ha mild erosion; a land area of 410.53 ha of erosion was severe erosion and a land area of 10 ha. Keywords: disaster, landslide

Effect of Heat Treatment on the Density and Surface Roughness Aluminum Alloy-Coal Bottom Ash Particle (5 Wt%) Composites for Bolts and Nuts Applications

Abstract: Metal composite or better known as Metal Matric Composite (MMC) is a combination of two or more materials, in which the metal as a matrix and ceramic as an amplifier exist to obtain the desired characteristics. To produce solid components and fine microstructure in its manufacture, the squeeze casting process has an approximate capability. In the manufacture of aluminum matrix composite, to obtain better mechanical properties such as hardness and strength, it is required existence of T6 heat treatment process. The purpose of this research is to analyze the influence of pouring temperature and pouring time variation on squeeze casting process to density and surface roughness of 6061 coal bottom ash composite. The research method consists in casting aluminum 6061 to melt at 660 °C and then adding coal bottom ash electroless plating and magnesium, the temperature is increased with variation of casting temperature 675, 700 and 725 °C. Pouring is performed for 60, 90, 120 s with following pressing under a 20 kgf load. Then we carry out T6 heat treatment. The tests include density testing and surface roughness testing. The results of the research on the density test showed that the value of density after the T6 heat treatment is greater. This shows the presence of expansion and shrinkage during the T6 heat treatment process. Based on the results of the surface roughness testing, the grown value of the roughness after T6 treatment is between 5 and 10% of the initial roughness value before T6.

Processing issues, machining, and applications of aluminum metal matrix composites

Abstract: Aluminum metal matrix composites (AMMCs) used in different industries from automotive to aerospace for specific purposes. Many problems hinder the full-scale industrialization of AMMCs but the main problems include wettability, particle distribution, porosity, and chemical reaction. These problems have explicit effects on mechanical, wear, and corrosion resistance properties of the composite materials. Therefore, it is essential to cope up with these problems for better quality of AMMCs. This paper focuses on issues related to AMMCs fabrication, corrosion resistance, wear resistance, machining parameter optimization, and chip analysis of AMMCs. Literature provides a guideline to researchers about present scenario of AMMC fabrication using stir casting process. Moreover, paper presents properties and applications of AMMCs.

Investigation of Industrial and Agro Wastes for Aluminum Matrix Composite Reinforcement

Abstract: Sustainable development of materials, environmentally friendly, and low-cost production is the background of this paper. The researchers focus on developing lightweight metal matrix composite materials with various reinforcements from chemical processes such as Al2O3, SiC, and graphite. These additions resulted improve in mechanical, physical, thermal, and corrosion properties of the materials. This paper offers the potential of alternative reinforcing materials that are inexpensive, easily accessible, and physical and mechanical properties equal to conventional particulates. Industrial and agricultural wastes that rich in oxide material can be used as an alternative material in metal matrix composite. Based on a review of the literature, various debris such as fly ash, bottom ash, rice husk ash, bean pod ash has been used as reinforcement in metal matrix composites. The literature states that the addition of particulates from industrial and agricultural waste improved the mechanical properties of composite materials.

Experimental study of quenching agents on Al6061–Al2O3 composite: Effects of quenching treatment to microstructure and hardness characteristics

Abstract: Aluminium based composite or well known as Aluminium Matrix Composites (AMC) can be improved in terms of mechanical properties with heat treatment. The quenching process parameters such as cooling rate, cooling agent and cooling temperature are predicted to affect the mechanical properties of the AMC. This study presents the results of a series of laboratory experiment to observe hardness ability of the Al6061–Al2O3 composites subjected to quenching agent and particle surface treatment. There are 3 variations of quenching agent and 2 types of reinforcement particle treatment. The quenching agent using water, oil, salt solution (brine), and 0% and 10% weight fraction of Al2O3 reinforcement. The hardness testing is conducted to the Rockwell B scale according to regulation of ASTM E−18. Obtained results indicated that the biggest distortion occurred as influences of quenching brine agent on each variation. The hardness of the 10E specimens (with treatment of Electroless Coating) is higher than the 10 N specimens (with treatment of Non-Electroless Coating). Based on this finding, it can be concluded that quenching agent and electroless coating treatment explicitly affected the hardness of Al6061–Al2O3 composites.

Kinetics of aluminum extraction from aluminum ash by leaching with sulfuric acid

Abstract: To explore the high value of aluminum ash development and utilization, factors (granularity of aluminum ash, leaching temperature, leaching time, sulfuric acid concentration, and liquid solid ratio...

Spatial Model Design of Landslide Vulnerability Early Detection with Exponential Smoothing Method Using Google API

Abstract: From 2005 to 2014, on average Indonesia experienced 1,295 natural disasters every year with year 2010 witnessed the most incidents. Landslide is the natural disaster with the most destructive effect and the highest death and missing human fatalities. This research produces the spatial model of early detection of landslide disaster vulnerability based on the rainfall data and soil condition using the single exponential smoothing method based on Google API. This model could predict areas vulnerable to landslide disaster and contributes in the systematic efforts in reducing human fatalities of natural disasters and mitigating natural disasters’ adverse effects.