| The structure of the automatic, continuous and real-time health monitoring system has became a new research direction and hotspot in the field of civil engineering, and the establishment of such a system would need to fit the civil engineering structure of the sensor. Lead zirconium titanate(PZT) piezoelectric ceramics is a kind of ceramic material with excellent piezoelectric, pyroelectric and ferroelectric properties,and the piezoelectric sensor with PZT as the substrate has the advantages of low cost, easy operation, real-time monitoring and so on.However, there are some problems such as the lack of fracture toughness and brittleness of the pure piezoelectric ceramic and cement based piezoelectric composites in the practical use. Not difficult to predict, and PZT powder in micro / nano scale chrysotile fiber will make it has a good toughening effect. Pb(Zr0.52Ti0.48)O3( PZT52/48) and Pb(Zr0.53Ti0.47)O3( PZT53/47)micro/nano-scale powder was prepared by sol-gel method.Combining with ultrasonic dispersing technology, PZT was mixed with chysotile fiber and illuminate cement in ethanol to prepare PZT/Ch F/PC. Having good sensing properties of PZT /Ch F/PC sensor would try to be preparation. The main research contents were given as follows:(1)PZT52/48、PZT53/47 was prepared by sol-gel method, and it was calcinated at 700 ℃, 800 ℃, 900 ℃, 950℃ temperature for preparing PZT powder to explore the influence of calcination temperature on it. The effects of temperature on the particle size distribution, crystal structure, microstructure of PZT52/48 and PZT53/47micro/nano powders and piezoelectric properties of PZT ceramics were respectively studied, and we found that PZT52/48 and PZT53/47 has the best perovskite crystal structure and plump crystalline grain at calcination temperature of 800 ℃. By comparing the piezoelectric constant and the relative permittivity of the dielectric constant:at 800 ℃, PZT52/48(d33 =89.5 p C/N、ζr=4.66(100Hz))and PZT53/47(d33=92.4 p C/N、ζr=5.41(100Hz)) piezoelectric properties is best, 800 ℃ could be thought of as PZT52 / 48 and PZT53/47 the best calcining temperature.(2)Take PZT53/47 as an example, the quality of 1:50, 1:100, 0.5:100 and 1:20 in the PZT53/47 powder was more than that of the strontium carbonate. It was found that the doping of strontium carbonate did not change its perovskite structure, and decreased the shape of PZT53/47 ceramic,so as to improve the piezoelectric properties of ceramic chip. However, in a certain range, the effect of the content of strontium carbonate on the piezoelectric and dielectric properties of PZT53/473 ceramics was not obvious.From the economic point of view, we can be considered 0.5:100 mass ratio for the best dosage, PZT53/47 doped with strontium carbonate of d33=123.0 PC / N, ζr=5.35 and mixing ratios of strontium carbonate PZT52/48 of d33=119.2p C/N, ζr=5.42(3)Taking PZT53/47 as an example, we study the relationship between the PZT of the piezoelectric properties and the quality of the gel and the specific surface area of the burn. Experiments show that: in a certain extent, it can be considered that the smaller the gel mass is the greater the pressure coefficient of the surface.(4)By ultrasonic dispersion method,PZT(PZT52/48 PZT53/47)and chrysotile fibers fiber and sulphoaluminate cement composite was prepared PZT(PZT52/48, PZT53/47) /Ch F/PC. By studying the crystal structure, apparent morphology and piezoelectric properties, PZT(PZT52/48, PZT53/47) /Ch F/PC perovskite structure was basically unchanged and the piezoelectric properties were good(PZT52/48/Ch F/PC,d33=32.5p C/N;PZT53/47/Ch F/PC,d33=33.1p C/N), which was considered to be necessary for the preparation of the sensor. After hydration, the perovskite structure of the perovskite structure and the piezoelectric properties of the PZT are destroyed seriously, and the piezoelectric properties(after hydration of PZT52/48/Ch F/PC,d33=7.6p C/N; After hydration of PZT52/48/Ch F/PC, d33=7.8p C/N) loss was too large, sothis step could be thought to be not necessary.(5)Preparing cement paste for water cement ratio were 0.5、0.33、0.25, the test pieces were made in two ways, One-time molding method and two-time forming method respectively. Compared the parameters such as the density, compressive strength and water resistance of the sample to determine the optimal concentration ratio of the polymer, and we could found that the density, compressive strength and water resistance of the 0.33 test blocks are better than those of the other. Among them, the density of one-time molding method cement block, compressive strength and contact angle were 99.245%, 38.6MPa, 130.05; the density, compressive strength and contact angle of the two-time forming method cement blocks were 99.592%, 37.3MPa and 131.03.(6)By comparing, we could know that one-time forming sensor(linearity, sensitivity, repeatability were 2.4%, 1.5, 3.42%) is smaller than the linear degree of the two-time forming sensor(linearity, sensitivity, repeatability were 3.4%, 1.2, 2.42%) higher sensitivity, better repetition, one-time molding sensor is more suitable for appli ation than the two-time forming sensor. |
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