| YANG Bo,LI Jie,LI He.Selection and Performance for Coating with High Dielectric Constant[J],45(8):40-44 |
| Selection and Performance for Coating with High Dielectric Constant |
| Received:April 20, 2016 Revised:August 20, 2016 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2016.08.007 |
| KeyWord:dielectric constant coating Al2O3 TiO2 spraying corrosion |
| Author | Institution |
| YANG Bo |
Shaanxi Yanchang Petroleum Company Institute, Xi′an , China |
| LI Jie |
Shaanxi Yanchang Petroleum Company Institute, Xi′an , China |
| LI He |
Shaanxi Yanchang Petroleum Company Institute, Xi′an , China |
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| Abstract: |
| Objective In order to overcome the low dielectric constant and short life of existing teflon coating, this work aims to seek and prepare coating with high dielectric constant and features like high wear resistance, good corrosion resistance, high hardness, strong insulating ability, good chemical stability and high temperature oxidation resistance and thus to improve the sensitivity coefficient and mechanical performance of probe, increase measurement precision and extend service life. Methods Ceramic powder like Al2O3-3%TiO2, Al2O3-13%TiO2 and Al2O3-20%TiO2 with three conventional particle sizes were selected and tested after being compared with the existing various types of coating. Their insulativity was evaluated respectively. Then one coating was chosen out for spraying test, permittivity measurement, corrosion test and extension test, and then was compared with teflon coating. Results The resistance of Al2O3-13%TiO2 and Al2O3-20%TiO2 between the coating and the substrate was respectively 0.57 MΩ and 0.42 MΩ, which indicated that the Al2O3-3%TiO2 coating had better insulativity. The particle size of Al2O3-3%TiO2 powder was 15~45 μm, and its particle distribution was dispersed. Its relative dielectric constant was as high as 290, 132 times of teflon coating. The coating surface was relatively uniform, but there was a small amount of porosity. After corrosion test, the mass loss of Al2O3-3%TiO2 coating sample was only 0.40 mg, far less than teflon coating 23.4 mg. For the extension test, if the load was 52 kN, the Al2O3-3%TiO2 sample would crack only when the sample was elongated for 20 mm; but the teflon coating peeled off completely when it was elongated for 7 mm. Conclusion Compared with teflon coating, Al2O3-3%TiO2 ceramic coating has better insulativity, higher dielectric constant (132 times of teflon coating), better spraying effect by virtue of its dispersible distribution of particle size, higher bonding strength between coating and substrate and stronger corrosion resistance. The experimental result shows that Al2O3-3%TiO2 ceramic coating can completely replace the existing teflon coating. |
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