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Rahman, Muh Budi Nur
Universitas Muhammadiyah Yogyakarta
Engineering

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Studi Optimasi Peningkatan Kekuatan Bending Komposit Berpenguat Serat Nanas-Nanasan (Bromeliaceae) Kontinu Searah Rahman, Muh Budi Nur; Suwanda, Totok; Diharjo, Kuncoro
Semesta Teknika Vol 11, No 2 (2008): NOVEMBER 2008
Publisher : Semesta Teknika

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Abstract

The objectives of this research are to observe the bending strength composite with bromeliaceae fiber with variations of alkali treatment duration, variations of fiber fraction volume and to observe the broken section characteristics. Materials used are bromilicea fiber, resin polyester, NaOH alkali and distilled water. The composite made with printing press methods. Dimensions of specimens and bending testing methods is done by to the standard ASTM D790 (bending test). Variables in this research are fiber fraction volume in the amount of 20-50% and the soaking times in alkali treatment are 0, 2, 4, 6 and 8 hours. Visualization of the broken section is shown in the macro picture. Highest bending strength and bending tensile occur in the composite with bromeliaceae fiber for 6-hour alkali treatment of 218.06 MPa and at the amount of 4.39% in fraction volume of 34.96%. Highest bending modulus occurs with 4 hours alkali treatment of 5.92% GPa. Composite with bromeliaceae fiber without alkali treatment has broken section characteristics fiber pull out, but the composite with alkali treatment has less fiber pull out characteristics.
Perbandingan Kekerasan dan Kekuatan Tekan Paduan Cu – Sn 6% Hasil Proses Metalurgi Serbuk dan Sand Casting Suwanda, Totok; Rahman, Muh Budi Nur; Ramdani, Deny Fajrur
Semesta Teknika Vol 11, No 2 (2008): NOVEMBER 2008
Publisher : Semesta Teknika

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Abstract

Metal production by sand casting and powder metallurgy indicates the advantage of metal process technology. Bearing materials must have hardness and compressive strength properties to withstand wear and pressure load. Material porosity provides the space for lubricant. The lubrication will decrease the friction and keep temperature low. Low friction and low temperature will increase the life time of bearing. The goal of this research is to compare the hardness, compressive strength, macrostructure and microstructure between Cu-Sn 6% alloy produced by sand casting and by powder metallurgy. During sand casting process, the metal was melted in the furnace and then poured in to the sand mold, whilst in the powder metallurgy process; the metal powder was compacted in the metal mould and then heated to a temperature below its melting point (sintering process). In this research, the powder was compacted at 200 MPa and then sintered at 800° C for 45 minutes. The observation of the microstructure showed that the Cu-Sn 6%  alloy produced by powder metallurgy possessed more porositythan produced by sand casting. The sand casting process produced the Cu-Sn 6% alloy with Brinell Hardness Number (BHN) of 47.97 kgf/mm2 and compressive strength of 680.8 MPa. The powder metallurgy process produced the Cu-Sn 6% alloy with Brinell Hardness Number (BHN) of 27.08 kgf/mm2 and compressive strength of 944.4 MPa.
Co-Authors Diharjo, Kuncoro Ramdani, Deny Fajrur Totok Suwanda