Tribological and mechanical behaviours of resin-based friction materials based on microcrack filling

To enhance the friction performance of resin-based friction materials,five types of specimens with different polymer ether ketone(PEEK)contents were fabricated and their physiomechanical behaviours were tested and,their tribological properties were investigated using a JF150F-II constant-speed tester.It was found that the addition of PEEK had a positive influence on the properties of the friction materials,and sample FM-3(the shorthand of‘Friction Materials-3’,containing 2 wt%PEEK)exhibited improved friction performance with a fade ratio and recovery ratio of 8.6%and 101.1%respectively.Among all samples,FM-4(the shorthand of‘Friction Materials-4’,con-taining 3 wt%PEEK)had the lowest specific wear rate with a value of 0.622×10^(−7)cm^(3)(N⋅m)^(−1)at 350℃.The PEEK can fill the microcracks in the composite at a high tem-perature and can also cover the hard abrasive particles to prevent them from directly damaging the composite.The findings from this study afford a foundation for studies to further improve the properties of resin-based friction materials.

β-cyclodextrin assists salt-resistance polymer flooding:Injectivity improvement

Polymer flooding method has attracted wide attentions in petroleum industry because of its relatively simple process equipment,low cost of agents and good performance on enhancing oil recovery.However,common polymer can hardly meet the technical requirements of the oilfields with high salinity.Existing salt-resistance polymer solutions get a large viscosity in high salinity condition by changing polymer molecules aggregation which,however,may result in the poor adaptability between polymer molecules and the pore sizes of reservoir.β-cyclodextrin(β-CD),a kind of chemical agent,is found to enhance the injectivity of salt-resistance polymer solutions by wrapping the hydrophobic groupings of salt-resistance polymer molecules.For a certain reservoir,the addition ofβ-cyclodextrin into salt-resistance polymer solution can balance the effect of plugging the layers with high permeability and the purpose of diverting to the layers with low and medium permeability.In this paper,viscosity of polymer solution is tested in condition of different concentrations ofβ-CD.On that basis,experiments on seepage characteristics are carried out to evaluate the injectivity of salt-resistance polymer solution.Finally,an appropriate concentration ofβ-CD,which is added into salt-resistance polymer solution,is chosen to adapt a certain reservoir with heterogeneity.

The influence of water disposal method on the property of chemical oil-displacement agent–taking Guan 109-1 area of Dagang oilfield as example

Aiming at the actual demand of Guan 109-1 block in Dagang oilfield,by means of instrumental analysis,chemical analysis,modern physical simulation,viewing polymer viscosity and seepage characteristic as evaluation index,the experimental research on the influence of water disposal method on the property of chemical oil-displacement agent was carried out.Results showed that through adding scaling agent,scale was formed because of the reaction between scaling agent and Ca^2+,Mg^2+ in the flooding water,which could enhance the viscosity of polymer solution.Through comparing the resistance factor and residual resistance factor of polymer solution which was respectively prepared with flooding water,softened water and scale,the resistance factor and residual resistance factor of polymer solution with scale was the largest,that of polymer solution prepared with softened water was second and that of polymer solution prepared with flooding water came last.Furthermore,scaling agent weakened the gelling effect between cross-linking agent Cr^3+ and polymer molecule chains.The earlier the crosslinking agent Cr^3+ was added,the larger the polymer viscosity,resistance factor and residual resistance factor of Cr3t polymer were.