制动片，刹车片中导热系数检测方案(导热仪)

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KYOTO ELECTRONICS MANUFACTURING CO.， LTD. Application Note Thermal conductivity measurement of brake pad for Vehicle Field： Nonferrous MetalApparatus： Quick Thermal Conductivity MeterAnalytical Method： Hot Wire MethodStandardDocument No.：EAPTM-0001Date of Issue： September 2013 1.Scope The brake pad is a key component of the disk brake system. Two brake pads are positioned between thecalipers and the rotors. When stepping the brake pedal to stop the vehicle， brake pads squeeze the brakerotor， thus the pressure and friction are applied to the rotor. As the result， the kinetic energy of rotor isconverted to the thermal energy by friction. Both brake pads and rotor are heated by the generatedfrictional heat. The thermal conductivity property of brake pads is important to keep the maximumperformance of brake system. The Quick Thermal Conductivity Meter makes the quality control of thermal conductivity of brake padseasy. The details are shown as follows. The Quick Thermal Conductivity Meter has an excellent operability and can be measured easy andrapidly. When starting to measure with holding the probe (Figure 1) to the sample surface of uniformtemperature， it will be possible to measure in only 60 seconds. 2. Measurement principle The probe is composed by the hot wire and the thermocouple put straight. The theoretical equation forthe temperature versus time is as follows； where A is the thermal conductivity，q is quantity of heat， Ti and T2 are temperature at the instants oftime t and t. This means that the temperature has a liner characteristic as a function of the logarithmicof the time. (Figure 2) The slope of this linear line will be large due to the temperature rise quickly for the low thermalconductivity sample. On the other hand， the slope will be small due to the temperature rise slow for thehigh thermal conductivity. Therefore the thermal conductivity of sample can be obtained from the slope of the temperature versusthe logarithmic of the time. Figure 1. Probe Figure 2. log(t)vsT(℃) graph 3. Precautions 1) The conductivity of sample is confirmed by using multimeter before starting measurement to selectthe probe. 2) The standard probe (PD-11) is for non-conductive sample and the insulated moisture-proof probe(PD-13) is for conductive sample. 3) The heater current value is decided that the temperature rise during measurement may becomewithin 5℃ to 20°C. Then the decided heater current value is set from [Heater Screen] of the mainunit and the appropriate heater current value has to be selected depending on the sample. 4) Make sure the sample size is 100mm(width) x 50mm(length) x 20mm(thickness) or more. Thesurface of contact side with probe makes flat to avoid the air gap between sample and probe. 5)When you measure the thin sample， please follow one of procedures as shown below； ① Pile up the sample or measure it on the material which has equivalent thermal conductivity.② Measure with the optional Software for thin Sheet Measurement. ※ For checking the effect of the worktable， if there is more than 5% deviation for themeasurement values between on the foamed polyethylene and the alumi cooling plate， the thinmaterial procedure has to be used. 6) The temperature of sample is made almost equal with the environment temperature before startingmeasurement. 4. Apparatus Main unit ：Quick Thermal Conductivity Meter Probe ： Sstandard probe [PD-11](*1) Insulated moisture-proof probe [PD-13](*2) *1； Standard parts of device *2； Use for the conductive， adhesive or wet sample The insulated moisture-proof probe is covered with the polyimide film toprotect the heater line， the thermocouple， and the base material of the probe.The sample that is possible to measure with the standard probe can bemeasured with the insulated moisture-proof probe too. 5. Measurement condition The samples are both conductive and non-conductive. The conductive sample is measured with the insulated moisture-proof probe， and the non-conductivesample is measured with both of the standard probe and the insulated moisture-proof probe. -Measurement conditionn- Sample Probe Heater current value I2 Non-conductive Standard probe 4.000 Conductive Insulated moisture-proof probe 4.000 The heater current value is set that the temperature rise during measurement may become within 5℃ tc20°C. The temperature rise is small when the heater current is small， so that the error and relativestandard deviation become large. Moreover， the temperature rise becomes 25℃ or more when the heater current is excessive， so that themeasurement is stopped. 16.Result The measurement result of the thermal conductivity of brake pad for vehicle is shown as below.The measurement is performed three times， and a mean value， standard deviation and relative standarddeviation are applied. -Ambient condition Temperature 23°C -Measurement result- Sample Non-conductive Conductive Probe Standard probe Insulated moisture-proofprobe Insulated moisture-proof probe Measurement value(W/mK) 0.8430 0.8407 1.3466 0.8332 0.8662 1.3479 0.8579 0.8416 1.3473 Mean value (W/mK) 0.845 0.850 1.35 Standard deviation(W/mK) 0.0124 0.0145 0.0007 Relative standarddeviation(%) 1.5 1.7 0.1 7. Summary The measurements of both the conductive and the non-conductive sample show an excellent resultwithin 3% of the relative standard deviation. The result can be confirmed there is no difference when the non-conductive sample is measured withthe standard probe and the insulated moisture-proof probe. Therefore， the insulated moisture-proof probe is recommended for the sample that has both conductiveand non-conductive. 8.Reference None KYOTO ELECTRONICS MANUFACTURING CO.，LTD. http：//www.kyoto-kem.com 京都电子工业株式会社-可睦电子(上海)商贸有限公司 上海市徐汇区宜山路333号1201室电话：021-54488867 电邮： kemu-kem@163.com 网址： http：//www.kem-china.com EAPTM- 京都电子工业株式会社-可睦电子(上海)商贸有限公司电话： 电邮： kemu-kem@ com网址：http：//www.kem-china. com/EAPTM- 汽车制动片导热系数的测量 制动片，也叫刹车片，在汽车的制动系统中，制动片是最关键的安全零件，所有刹车效果的好坏都是制动片起着决定性的作用。两个制动片位于卡钳和转子之间。当踩下制动踏板以停止车辆时，制动衬块挤压制动转子，从而将压力和摩擦施加到转子上。其结果是通过摩擦将转子的动能转化为热能。制动片的导热特性对于保持制动系统的最大性能是重要的。快速导热仪可以对刹车片的导热系数进行质量控制。快速导热系数仪具有优异的操作性，并且可以容易且快速地测量。仅需将将传感器置于温度均匀的样品表面，测量时间仅需60秒。