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Pan G.,Shanghai University | Guo Q.,Shanghai University | Ding J.,Shanghai University | Zhang W.,Shanghai University | Wang X.,Shanghai Electrical Cable Research Institute
Tribology International | Year: 2010

To obtain a composite coating possessing both good conductivity and high wear resistance, a series of coatings with conductive graphite and epoxy resin were designed. The seepage critical value (SCV) of conductive coatings was used to identify the transformation between continuous phase and dispersed phase for graphite/epoxy composite coatings. Before SCV, the coatings were insulated with epoxy resin as continuous phase and the wear behavior was primarily characterized of adhesive wear with local adhesive spalling of epoxy resin. After SCV, the coatings appeared conductivity and the surface resistance decreased monotonically with the increase of graphite content. Both the curves of friction coefficient vs. graphite content and wear rate vs. graphite content showed the same model with two valleys at graphite content of 30% and 50%, respectively. At graphite content of 50%, an optimal solid lubricant film was obtained which leaded to the lowest friction coefficient and wear rate, due to a possible dynamic equilibrium between the transfer and spalling of debris. The tribological behaviors of these coatings were evaluated using a ring-on-block tribo-tester under dry sliding friction. Crown Copyright © 2009. Source


Liu J.,Harbin University of Science and Technology | Li X.,Harbin University of Science and Technology | Gao H.,Shanghai Electrical Cable Research Institute | Guo H.,China National Offshore Oil Corporation
Gaodianya Jishu/High Voltage Engineering | Year: 2014

The umbilical cables used for subsea oil production have complex units, so the traditional analytical method is unable to determine their insulation thickness and ampacity. To solve this problem, we used a finite element method to calculate and analyze the electric filed and temperature field in umbilical cables. We also compared umbilical models with different insulating materials, different insulation thicknesses and different structure forms, and then proposed a method of optimization design based on ANSYS, for determining the ampacity of umbilical cable. It is shown that the relative positions of units in umbilical cable hardly affect the distribution of electric field, while the electric field mainly focuses on the phase-phase line of inner conductor in the units. According to analysis of electric field, the critical thickness of crosslinked polyethylene(XLPE) is 0.25 mm. As for the umlicical cables with different structures, the one with central steel tube has ampacity up to about 60 A, which is superior to the type with central cable. However, there are slight differences in peak electric field and amplicity between XLPE cable and ethylene-propylene rubber (EPR) cable. Conclusively, the finite element method is applicable for determining the insulation thickness and ampacity of umbilical cables. Source


Chen J.,Shanghai University | Chen J.,Chizhou College | Guo Q.,Shanghai University | Zhang S.,Shanghai University | And 2 more authors.
Procedia Engineering | Year: 2012

The plastic alloys of PEEK/PEI/PES were prepared with extrusion molding at 370°C in ratios of 70/30/0, 70/25/5, 65/30/5, 60/30/10, 60/35/5 (w/w). Friction and wear behaviors of the alloys were investigated under dry sliding contact condition. And wear resistances of PEEK/PEI/PES alloys were considerably improved than pure PEI and PES. The friction coefficients of the alloys were higher than the pure PEEK for 0.2-0.3. The specific wear rates of the pure PEI or PES were 4-6 times as large as the specific wear rate for the alloys of PEEK/PEI/PES, and the specific wear rate for the alloys of PEEK/PEI/PES is 7~9 times as large as the specific wear rate of the pure PEEK. The plastics alloys would produce the transferred film containing PEEK on the steel counterface. However, the transferred film of pure PES or PEI was not found on the steel ring surface. A thin symmetrical and tough transferred film in the worn steel surface against the alloy specimens could reduce friction and wear. © 2012 Published by Elsevier Ltd. Source


Chen J.,Shanghai University | Chen J.,Chizhou University | Guo Q.,Shanghai University | Zhao Z.,Shanghai University | And 3 more authors.
Journal of Applied Polymer Science | Year: 2013

PEEK/PEI/PES plastics alloys in weight ratios of 70/30/0, 70/25/5, 65/30/5, 60/30/10, 60/35/5, and the three kinds of single high performance engineering plastics 100/0/0, 0/100/0, 0/0/100 were prepared by twin-screw extrusion molding. A single glass-transition temperature (T g) of each alloy in the former five kinds of the plastics alloys could be measured by DSC and always rose to higher one than that of the pure PEEK by about 20°C. The crystalline degrees of these alloys could also ascended to more than 35.81% higher than that of the pure PEEK, especially for the alloy of the ratio 60/30/10 reached the maximum crystalline degree 37.76%. Adding PEI or PEI and PES, the crystalline temperatures of the PEEK alloys were decreased. The wear resistances of the alloys under dry sliding condition were considerably improved compared with pure PEI or PES, and the specific wear rate of the pure PEI or PES were four to six times as large as that of the alloys. However, the specific wear rates of the alloys were six to eight times larger than that of the pure PEEK, and the friction coefficients of the alloys were higher than that of the pure PEEK for 0.2-0.3. The polymeric transferred film on the steel ring surface against the alloys could be found, but no film on that against pure PES or PEI was found. © 2012 Wiley Periodicals, Inc. Source


Chen J.,Shanghai University | Chen J.,Chizhou College | Guo Q.,Shanghai University | Zhao Z.,Shanghai University | And 2 more authors.
Procedia Engineering | Year: 2012

The PEEK/PEI/PES plastic alloys were processed by twin-screw extruder at 370°C with five mass ratios of 70/30/0, 70/25/5, 65/30/5, 60/30/10, and 60/35/5, respectively. Their thermal properties and crystallization behavior were investigated by the differential scanning calorimetry. The measured results showed that all the plastic alloys had a single glass-transition temperature (Tg), which revealed good compatibility among the three members of PEEK, PEI and PES. For the alloy with the mass ratio of 70/30/0, the minimum Tg of 160.6 °C was obtained, but the alloy of 60/35/5 had the maximum Tg of 164.5 °C, which indicate that PEI, PES and the amorphous plastics could increase Tg of the PEEK alloys and was 20°C higher than that of pure PEEK. The melting points (Tm) of these alloys were from 334.4°C to 336.3°C and their crystallinity degrees were from 35.8% to 37.8%, whereas both were slightly higher than that of pure PEEK. However, the cold crystallization temperatures of the alloys were lower than that of pure PEEK, which could be attributed to the reason that the rheological properties of the alloys were improved by PEI. Tensile strength of the plastic alloy with the ratio of 60/30/10 presented the maximum value of 108MPa and was higher than that of pure PEEK. After thermal ageing at 158°C (below T g) or 178°C (above Tg) respectively for 168h, their tensile strengths decreased only slightly, but elongation rates at break reduced significantly, of which thermal ageing above Tg would recede the elongation at break more severely. The plastic alloy of 60/30/10 could be used as the cable insulating jacketing for nuclear power station. © 2012 Published by Elsevier Ltd. Source

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