Piezoelectric ceramics are widely used in the field of knitting. Suzhou Hefang is currently the only supplier in China that can provide both warp knitted piezoelectric ceramics and weft knitted piezoelectric ceramics. Warp knitting piezoelectric ceramics are widely used in well-known warp knitting machines at home and abroad, such as KARL MAYER, TIANYUAN... ; also used in well-known weft knitting machines at home and abroad: Mayer&C, Terrot, Santoni, Lonadi, Fukuhara...
Some dielectrics (such as quartz, tourmaline, potassium and sodium tartrate and other crystals) will generate charge displacement under the action of force in a specific direction, so that a potential difference will appear between the surfaces at both ends; The dielectric deforms elastically. The former is called "positive piezoelectric effect", and the latter is called "inverse piezoelectric effect" or generally called "electrostriction", collectively referred to as piezoelectric phenomenon. Piezoelectric materials used as sensors require strong piezoelectric effect, good temperature stability and aging performance. There are two types of piezoelectric materials, single crystal and polycrystalline. The former is represented by quartz crystal, which is characterized by good temperature stability and aging performance, and a very high Q value; the latter is represented by lead titanate zirconate piezoelectric ceramics, which is characterized by easy fabrication, adjustable performance, and easy mass production. . Piezoelectric materials have been widely used in sensors such as force-sensitive, sound-sensitive, thermal-sensitive, light-sensitive, humidity-sensitive and gas-sensitive. The following table lists various sensors made of piezoelectric materials.
Pyroelectricity of ceramics
There are spontaneously polarized crystals, and their surfaces are usually held in electrical equilibrium by trapping charges in the atmosphere. When the temperature changes, the crystal in the state of electrical equilibrium, its internal spontaneous polarization emission changes correspondingly with the temperature change. Because the change of the crystal surface charge cannot keep up with the change of the spontaneous polarization inside the crystal, the charge can be observed on the crystal surface. Figure (a) shows the initial electrical equilibrium state of the crystal surface, Figure (b) shows the change of spontaneous polarization inside the crystal, and Figure (c) shows that the crystal reaches a new equilibrium state. In the state of (b), surface charges can be observed. When the temperature changes, the induced charge is released on the crystal surface due to the change of the spontaneous polarization inside the crystal, which is called the pyroelectric effect. If electrodes are installed on both sides of the pyroelectric body, and the two electrodes are indirectly loaded, the surface charges released due to temperature changes will form a thermal current through the load. http://www.sz-cotex.com