10-08-2012, 01:02 PM
Investigation on Two-Body Abrasive Wear Behavior
Investigation on Two-Body .docx (Size: 507.65 KB / Downloads: 29)
Materials
E-Glass woven fabric 210 gsm were obtained from M/s. Reinforced Plastics Industry, Bangalore. The glass fabric of 8 mill bidirectional with fiber diameters of 5-12 μm (Fig. 1) was used as reinforcement. Bi functional epoxy-diglycidyl ether of butane diol (LY 5052)-cyclo aliphatic amine (HY 5052) (room temperature cure system) mixture- 100:38 w/w were obtained from M/s. Huntsman Advanced Materials Mumbai, India. The LY 5052 is a clear liquid resin, with a viscosity at 250 C is 1000-1500 mPa and specific gravity 1.17. The hardener HY 5052 is a liquid with its viscosity 40-60 mPa and specific gravity 0.94. The commercially available silicon carbide powder was obtained from M/s. Silicarb Recrystalized Pvt. Ltd., Bangalore. Its particle size ranged from 20-75 μm was used as filler material.
Fabrication of Composites
A bidirectional glass woven fabric cut as per the required dimension, a bifunctional epoxy resin and hardener (epoxy-diglycidyl ether of butane diol/cyclo aliphatic amine) mixture in the ratio of 100:38 by weight was used as a matrix. The weight percentage of glass fabric in composite was 48 + 2 %. The formulation of the composites is given in Table 1. A releasing agent is applied on the smooth surface of the mold for easy removal of the composite stack and to obtain accurate surface finish. A typical hand lay-up procedure consists of placement of fabric one above the other, for each placement of fabric a well stirred mixture of epoxy resin and hardener is applied. The exposed side of the stack was covered by cellophane membrane and sealed round the periphery by using suitable sealant. The laminate was cured under the pressure of 14 psi up to 24 hours. To prepare SiC filled composite a 6 wt. % of filler is incorporated into the epoxy resin mixture and stirred well until uniform distribution of filler. The laminate of dimension 200 mm x 200 mm x 2.8 + 0.2 mm was fabricated and the test specimens for the required dimensions were cut using a diamond tipped cutter.
Techniques
The impact strength of the specimens was measured by using Notched Impact Tester (M/s. International Equipments, Mumbai, India) as per ASTM D-256 test method. The surface hardness of the composite was measured using shore D Durometer (M/s. P.S.I Sales Pvt. Ltd., India) as per ASTM D 2240 specification. Two-body abrasive wear test was conducted by using a pin-on-disc machine as per ASTM-G99. The surface of the sample (5 mm x 5 mm x 2.8 mm + 0.2 mm) glued to a pin of dimensions 10 mm diameter and 25 mm length, which comes in contact with water proof silicon carbide (SiC) abrasive papers. The SiC paper is glued on a steel disc by using a suitable adhesive. For different abrading distances new SiC abrasive paper has been used. Scanning electron microscopy (SEM) photo of SiC abrasive paper of 600 and 1000 grit size before the wear test is shown in Fig. 2a
and 2b respectively.
The abrasion wear test was conducted on a track of 20 mm diameter. The composite specimens were abraded against 600 and 1000 grit SiC papers at a constant load of 10 N, at 200 rpm and at four abrading distances viz., 25, 50, 75 and 100 m under multi pass condition. The surface of the samples is cleaned with a soft paper soaked in acetone before the test. The specimen weight is recorded using an electronic balance (made A&D GR-300, 0.1 mg accuracy). The difference between initial and final weight of the specimen were measured as the slide wear loss. A minimum of three trials for each specimens was conducted to ensure repeatability of test data. The frictional force is measured by attaching a force transducer on pin-on-disc machine and it touches the loaded lever arm (Fig. 3). The coefficient of friction was obtained by dividing the tangential frictional force by the applied normal force. The weight loss was converted into volume loss by using a measured density of the specimen. The specific wear rate (KS) was calculated using following mathematical relation: