Showing 3 results for Phenolic Resin
H.r. Salehi, S.m.r. Khalili,
Volume 30, Issue 2 (12-2011)
Abstract
In the present work, thermal and mechanical behaviors of phenolic resin are investigated. This polymer can be used as a matrix for carbon-carbon composites. To find out the best heating process, five different cycles are used for curing the polymer and flexural strength of the specimens are obtained. The cycle with maximum strength is used for the next steps. Then, the oxidation behavior of specimens is studied at different temperatures. The results show that the polymer can withstand temperature about 350°C without significant weight changes. Carbonization of phenolic resin is studied by four different cycles at 1100°C. Oxidation of carbon obtained from carbonization cycle is analyzed extensively and shows no weight change until 550°C. The microstructure of specimens is also investigated by SEM. By additining SiC micro particles to phenolic polymer, the strength change is achieved.
H.r. Salehi, S. Salami, M. Atarian, O. Ozhdelnia,
Volume 32, Issue 1 (6-2013)
Abstract
Carbon fiber composite is one of the most important materials in aerospace engineering applications. For fabrication of this composite, optimum polymerization and carbonization cycles of phenolic resin were obtained [1]. Then, carbon/phenolic composite was fabricated by mixing different weight percentages of T700 carbon fiber with phenolic resin, and the flexural strength of specimens was examined.The samples were pyrolyzed at 1100°C to form high temperature phenolic matrix. Because of high porosity of samples, the composite was impregnated to increase the density and reduce porosity. The maximum flexural strength of samples was obtained with 40 wt. % of fiber. With addition of TiO2 and ZrO2 nanoparticles to carbon/phenolic composite, thermal and mechanical improvement was measured. The samples were examined by ablation test and microstructures of composites were analyzed by SEM.
M. Shirvani, M. Mashhadi, M. Yosofi,
Volume 38, Issue 4 (1-2020)
Abstract
In this research, solid state carbothermal synthesis of HfB2 Nano powders was investigated. For this purpose, HfO2,H3BO3, carbon active or phenolic resin were used as raw materials for carbothermal reaction. After 2-4 hours of milling the raw materials by a planetary ball in an ethanol media, the mixture was heat dried and pressed in to disks under pressure of 20-30 bar. The disks were then placed in a graphite crucible and heat-treated at 1500–1600 °C for 1 hour under flowing Ar atmosphere. The powder product was analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and backscattered electron (BSE) imaging. The heat treatment temperature, amount of boric acid, milling and heat treatment time were recognized as four factors influencing synthesis and size of HfB2 powder particles. SEM images reported irregular morphologies with a particle size of about 2-4 µm for HfB2 powder. The best sample was obtained at a molar ratio of HfO2 : phenolic resin carbon: boric acid = 1:5:5 at 1600 °C after 1 hour of heat treatment. XRD results confirmed synthesis of pure HfB2 with a crystallite size of about 60 nm.
