Rice polycrystalline powder and ceramic components, including powders, have been previously reported.
2, thus, the shorter the response time, the better. The test proves that the time required for the above component resistance value to reach a constant value in the process of moisture absorption is basically the same as the dehumidification time. The average time is 3 minutes, then the response time is r=110s. This value is reported. K2-Fe23 humidity sensor response time (l'OOs) close to 丨 5. LazBai-zTiOs ceramic component moisture resistance characteristics curve 3.3 LazBTiOs ceramic component of the wet hysteresis characteristics of wet hysteresis refers to the process of moisture absorption and desorption, two resistance - wet The curves do not coincide, so the hysteresis loop is formed. The maximum humidity difference between the moisture absorption and desorption curves in the loop is defined as hysteresis, and the hysteresis of the component is as small as possible. The hysteresis test of the above components according to the conventional method shows that there is little difference in the resistance value during the process of moisture absorption and desorption, and the hysteresis does not exceed 4%, which indicates that the hysteresis characteristics of the components meet the requirements. The mechanism of hysteresis can be inferred that when water vapor molecules are adsorbed on the surface and internal pores of the ceramic grains, there is an attractive force between the molecules. When the moisture molecules are removed during dehydration, they can only leave the matrix of the moisture sensitive elements. Dehumidification requires a process that produces hysteresis.
IBaHTiCb Ceramic Element Humidity Sensitivity Anti-Jamming Negative Test In a negative temperature test at a working temperature of 450°C, the resistance of the device under the seven atmospheres was measured as a function of atmospheric concentration. The results show that only the ceramic component with doping ratio of 9 mol% La = 0.09 and calcined at 1350°C/lh has a certain response to CH3CH=CH2 (propylene), but the resistance does not change by orders of magnitude; The components of the other proportioning and sintering systems are not sensitive to the seven atmospheres (including ethanol vapor), that is, the resistance is similar to that in the air, and they are all in a high-impedance state (i>lMfi). Although the component operating temperature was increased, the components were still insensitive to the seven atmospheres. This indicates that the ceramic moisture-sensitive characteristics are very selective, and the anti-interference ability of the seven atmospheres is high.
The SEM morphology and microstructure of La:cBaizTi03 ceramics probes show the SEM appearance and microstructure of the representative ceramic probes for moisture sensors. It shows a polycrystalline morphology with uniform grain size distribution. For 0.7/mi, the grain shape is regular, showing a quasi-cubic crystal type, or pseudo-cubic crystal type, which is actually the type of perovskite tetragonal (square) crystal phase previously demonstrated. W. Description of dried gel raw powder through buried electrodes And pressure molding (1.6MPa/3min), and then high-temperature sintering into porcelain, this process makes the grain from the nanometer scale to micron scale, the degree of crystallization and porcelain become intact, resulting in obvious crystal face and grain boundary As well as the voids and channels, there is a suitable inner surface and corresponding pore structure. This can be confirmed by the fact that the titled doped yttrium tetronic acid tetragonal phase polycrystalline ceramics are indeed produced, and the ceramic with moisture sensitivity characteristics is also examined. The microstructure provides a credible basis for exploring the mechanism of moisture sensitivity.
The angularity of the crystal grain in the end face of the YUZHONG ceramic probe is more distinct than that on the side surface. This is due to the wear and contamination of the probe side during assembly and observation.
Ceramic SEM Microstructures La: cBanTi03 Moisture Sensitive Elements AFM Morphology and Microstructure of Ceramic Probes The surface appearance of the ceramic probes was analyzed using an Atomic Force Microscope (AFM). The figure shows that the ceramic surface is uneven. High surface roughness, characterized by porosity and voids, is one of the reasons for the characteristics of moisture-sensitive ceramics (semiconductor modification by erbium doping is another cause of moisture sensitivity).
All-element analysis of X-ray fluorescence spectrometer XRF for moisture-sensitive ceramic probes A representative probe was qualitatively analyzed based on the relationship between the wavelength of the characteristic fluorescence spectrum and the atomic number (limits of space, the chart is abbreviated); and it was quantified using the basic parameter method. Analysis of the mass percentage of all elements (Table 1) shows that: the results of all-element analysis and the experimental design of the doping ratio are basically in line with the reasons for some deviations are mainly raw material purity and instrument error.
Ceramic Surface AFM Morphology Chart 1 LazBaiTiOa Ceramics XRF Quantitative Analysis of All Elements 3.8 Possible Mechanisms for Semiconducting and Internal Stress Modification of Erbium-doped Barium Titanate Moisture Sensitive Ceramics On the one hand, La3+ does not substitute for Ba2+W due to Erbium doping. As a result, there is a more positive charge. In order to maintain electrical neutrality, Ti4+ will capture a free electron and change its price to I7,8 which is bound loosely under certain conditions, such as suitable microstructure of the ceramic and water molecules induced Synergistic, easy to enter the conduction band and participate in the conductive and significantly reduce the resistance, so that the barium titanate can be semi-conductive modified to become a functional material with humidity sensitive properties On the other hand, the smaller radius La3+ (r=0.106nm) Substituting the larger radius Ba 2+ (r=0.136m) will reduce the lattice distortion of the tetragonal phase. 4 Conclusions 1. Humidity-sensitive ceramic components have good resistance to wetness characteristics in the operating humidity range (Brother=32.8) %93.6%), average sensitivity>S=5xl04kfVRH(%), linear correlation factor of resistance-wet graph 7=0.998, good reproducibility, response time r=110s, hysteresis hysteresis below 4%, for H2 ,CH4,CH2=CH2,CH3CH=CH2,CO,C6H6 and CH3CH2OH (g) The seven atmospheres have no gas/wine sensitivity characteristics, so the moisture sensitive ceramic components have high anti-interference ability and good moisture sensitivity.
The SEM and AFM tests on the microstructure of the ceramics show that the average size of the ceramic grains is 0.7 pm, and the appearance of the grains is regular. It is a perovskite tetragonal phase polycrystalline ceramics with high surface roughness and a suitable inner surface and pore structure.
The all-element analysis results of XRF are close to the doping ratio, which confirms that the yttrium doped yttrium doped barium doped yttrium-doped ceramics are semi-conductive to the humidity-sensitive ceramics, and thus have the moisture sensitivity characteristics. The mechanism may be La3+. Valence replaces the titanium ion induced by Ba2+, ie, Ti4+ captures a free electron and changes its price to Ti3+. The electron easily enters the conduction band under the synergistic effect of the appropriate ceramic microstructure and water molecules, which significantly reduces the resistance. In addition, the radius is smaller. The substitution of La3+ for Ba2+ with a larger radius reduces the tetragonal distortion of the ceramic, so that the anisotropy of the crystal lattice becomes smaller, so that the crack caused by the internal stress of the ceramic after cooling the ceramic is reduced.
Chain Link Fence also referred to as wire netting, wire mesh fence, chain wire fence, cyclone fence, hurricane fence or diamond mesh fence is a type of woven fence usually made from galvanized or green color/black color PVC-coated steel wire. The wires run vertically and are bent into a zig-zag pattern so that each "zig" hooks with the wire immediately on one side and each "zag" with the wire immediately on the other. This forms the characteristic diamond pattern seen in this type of fence.
Application:
Widely used in highway, railway, highway and other fence facilities. Also used for interior decoration, raising chickens, ducks, geese, rabbits and zoo fence. Fence of mechanical equipment,mechanical equipment of the transmission network. Sports venues fence, the road greening fence.
diamond wire mesh,rhombic wire mesh,PVC coated Chain link fence
Anping Bochuan Wire Mesh Co., Ltd. , https://www.wiremeshbocn.com