Study On The Preparation Of SiAlCN High-temperature Sensitive Materials And Its Electrical Properties

In some extreme environmental conditions,the rapid and accurate monitoring of physical quantities has made strict demands on the sensors in aerospace field.They are not only tolerant of extreme conditions,but also always maintain stable special performance.Extreme environment mainly includes high-temperature,high-pressure,corrosion,oxidation and so on.Sensing materials need to tolerate extreme environmental conditions in order to monitor physical changes over a long period of time.Traditional sensing materials have not met these requirements,so it is necessary to find new materials.It is found that Polymer Derived Ceramics(PDCs)have excellent properties,especially high-temperature semiconductor performance,which is one of the best candidate materials for new sensing materials.In this paper,SiAlCN organic precursors were successfully prepared by grafting modified polysilazane(PSN-1)with aluminum isopropoxide(AlP),firstly.The organic precursor is exposed to air for a short period of time without oxidation and can be stored in a closed container for a long time.Secondly,SiAlCN organic precursors were cross-linked and pulverized to obtain ultrafine powders.SiAlCN precursor powders and liquid precursors were mixed in proportion,and then cold isostatic pressing was carried out before molding to obtain dense SiAlCN ceramic body.On the basis of that,the SiAlCN ceramic sensitive materials were obtained by micro-mechanical drilling and connecting the electrode with liquid SiAlCN organic precursor in vacuum.Finally,prepared SiAlCN sensitive materials were tested for high-temperature electrical properties.The temperature-resistance of sensitive materials were tested,and analyzing the conductive mechanism of sensitive materials.The high-temperature reproducibility and stability of SiAlCN sensitive materials were analyzed by testing the effect of temperature cycling and insulation on the high temperature electrical properties of SiAlCN ceramic sensitive materials.The results show that SiAlCN sensitive materials with excellent properties have been prepared by the above methods.SiAlCN sensitive materials have high-temperature resistance characteristics.Their resistance gradually decreased with temperature,and the sensitivity is excellent.The conductive mechanism of SiAlCN sensitive materials shows that the low temperature conforms to the short-range jump mechanism,and the medium temperature conforms to the conduction mechanism with the tail state,and the high-temperature conforms to the extended state conduction mechanism.SiAlCN sensitive materials have good high-temperature repeatability,stability,can be used as high-temperature sensitive materials.