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The synthesis of nanoparticles using thermal DC plasma method is a simple method for ease of installation and high efficiency is due to the rate of precursor that can be controlled. Micro-sized aluminum powder is synthesized using thermal DC plasma undergoing a process of evaporation as it passes through high temperature plasma flame, where kemuadian oxidized aluminum particles which evaporates the particles are split and binds with oxygen to form aluminum oxide or also known as alumina (Al2O3). In this experiment, the flow rate of oxygen plasma parameters at 35 SCFH (Standard Cubic Feet per Hour) and 20 amperes flows with precursors rate variation of 1.16 g / min, 3.19 g / min, and 3.5 g / min. Precursors used is 88 micro sized aluminum powder. To determine the morphology of nanoparticles of alumina testing scanning electron microscopy (SEM), the morphology form of nanosphere. Results of the analysis showed that the rate of precursor low causing agglomeration level slightly while the higher rate of precursor agglomeration rate also increased. At the rate of precursor 1.16 g / min, nanoparikel undergo agglomeration with an average particle size of 36.55 nm, and then at a rate of 3.19 gr precursor / mnt an average particle size of 46.49 nm, and at a rate of 3.5 gr / mnt an average particle size of 46.49 nm. The powder nanoparticles were then characterized using X-ray defraksi (XRD) where all alumina nanoparticles were synthesized showed alumina phase that is formed is a phase δ-Al2O3. Keywords: Alumina nanoparticles, DC Thermal Plasma, morphology, precursor rate, nanoparticles size, SEM, XRD.

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Cotton fibers currently use in many industries textiles, easy gotten in the market, and a cheap price. Using of fiber would be able to solve the environtment problems, reduce the metal using, particularly in the oil and gas industries. In this study, composite pipes are made by cotton fibers as reinforcement, particles of montmorillonite as filler, and unsaturated polyester as matrix. From that consideration this study was conducted to obtain that analysis of tensile strength composite cotton fibers. With the pattern of variation woven fiber direction angle towards the corner fibers 450, 550, 650, 750, and 850. From the test results the highest tensile strength values is obtained by a composite pipe with fiber direction angle of 850. The test results showed that the tensile strength of the cotton fiber reinforced composite pipe with direction of 450 angle fiber is 3.76 MPa, for direction of 550 angle fiber tensile strength is 1.28 MPa, for direction of 650 angle fiber tensile strength is 10.691 Mpa, for direction of 750 angle fiber tensile strength is 14.465 Mpa, and for direction of 850 angle fiber tensile strength 28.617 MPa. Keywords: Cotton fiber, unsaturated polyester, filament winding method, montmorillonite, Tensile Strength

Corrosion is a form of damage that occurs in metals. The main factor is the cause of the corrosion environment. A53 steel is a type of low carbon steel and a steel material types that are widely used for pipe applications. The use of a corrosion inhibitor is one way of preventing corrosion. Anthocyanin substances contained in purple yam can be made in a natural inhibitor, because the substance is an antioxidant anthocyanin which is an oxidation inhibitor. Variables used were varied concentration of 0 ppm, 2000 ppm, 4000 ppm and 6000 ppm. This study aims to determine the rate of corrosion, purpel sweet potato extract efficiencies and changes in microstructure. The method used in this study is experimental, inhibitor efficiency analysis, ANOVA test and analysis micro photo. The results showed that the material is corroded by pitting corrosion and uniform shape. Values on concentration lowest corrosion rate of 0.0044 mmpy 6000 ppm and 6000 ppm at the highest efficiency of 72.70%. Keywords: anthocyanin, steel A53, natural inhibitor, purple sweet potato.