Friction Materials Learning From Honeycomb Structure

Friction materials for car and truck disc brake pads are typically complexcomposites which can be transformed energy and provided stable frictionperformance over a range of operating conditions of vehicle, which can beexhibited acceptable wear life, and produce minimal noise and vibration. Kineticenergy is released in heat energy, noise and/or vibration in brake. Motion and forceare transferred through friction of the clutch in vehicle, machining tool and others.So, the properties of friction materials impact the operating properties and safty ofmachines closely and directly.In this work, a basic content of fillers was determined for the bakelite frictionmaterials reinforced with composite mineral fibers. It was required that the fillingmaterials should benefit friction and wear properties of friction materials stable,keep the materials an appropriate wear rate, and decrease noise due to friction. Theeffects of these basic materials on the friction materials were analyzed. It wasdemonstrated that Sb2S3 play a role of binding adhesive of friction materials in hightemperature, which is an friction-increasing material. Nevertheless, noise andvibration are increased if the content of Sb2S3 is over 6%wt in friction material.Vermiculite is a mineral material possessing such functions as better frictionreduction, sound absorption, anti-wear rate. It was shown that porous iron powder,alumina powder and molybdenum bisulfide are materials which can stabilizetribological performance of the friction material.Regression analysis of friction coefficient and impact strength of the frictionmaterial with technical parameters during it preparation were conducted byuniformity experiment design method and the following regression equations wereobtained. Y₁ = 0.523282 -1.791×10^-3 X₁ -1.0791×10^-5 X₁ +1.2704×10^-5 X₃X₁ Y₂ = 1249.828571+ 74.842857X₁ -98.994286X₂ -1.978143X₁² + 2.921714X₂ X₁Where, X1 X2 and X3 are the molding pressure, duration of keeping heat pressureand molding temperature, respectively; Y1 and Y2 are fricion coefficient and impactstrength of the friction material, respectively. The three-dimensional graph of theabove regression equations were represented by MATLAB program. It was foundthat the molding pressure and temperature have obvious interaction on the frictioncoefficient and impact strength of the friction material. Friction coefficientdecreased with the molding pressure for a constant molding temperature andincreased with the molding temperature for a constant molding pressure. It can beobserved that the molding pressure and pressure-keep duration had interaction froma contorted back worn surfaces. Impact strength increased and then decreased asreduction of the molding pressure for a constant pressure-keep duration. Theimpact intensity increased with the length of the pressure-keep duration for aconstant molding pressure more than 40 MPa, while decreased for a constantmolding pressure less than 40MPa.The effects of the bakelite to the friction and wear characteristics of frictionmaterials was investigated in the experiment method of single factor, and it wasfound that the optimal value of bakelite in the friction material was 16-20%wt.Friction coefficient increased with the bakelite content when bakelite content wasless than 16%wt. The wear rate of the friction materials decreased and the impactstrength and hardness of the friction materials increased with the bakelite contentwhen the bakelite content of friction material was less than 20% wt.Friction materials simulating the honeycomb structure was designed andprepared using prefabricated granular and layered material with sizes of less than2.5 mm and a second adhesive on the basis of the principle of the structuralbionics. . It was demonstrated that the bionic structure simulating the honeycombof the friction material can provide a stable tribological property and a reducedwear rate and, especially, the content of bakelite resin of the friction material can bereduced, to 9.4%wt, which would decrease the cost of the friction materials. Thestructural and active mechanism of the second adhesive in the friction material wasanalyzed. The sulfuration reaction played a part of adhesive in the bionic friction...