Fabrication And Properties Of 0-3 Slag/Fiy Alkali-base Piezoelectric Composite

Piezoelectric composite is a kind of multifunctional intelligent material.It has the characteristics of matrix material and good piezoelectric property.It can be made into sensors and applied to health monitoring in practical projects.Polymer piezoelectric composites and cement-based piezoelectric composites are the research hotspots in the field of piezoelectric materials.Polymer piezoelectric composites have the advantages of good flexibility and easy molding,but the compatibility with concrete materials commonly used in practical engineering is poor.Cement based piezoelectric composites have good compatibility with concrete components,but cement is porous material,and its pores will easily cause polarization breakdown of piezoelectric materials;at the same time,cement is a high energy consumption building material,and the carbon emission of cement production accounts for 5%～8%of the world’s total carbon emissionAlkali activated cementitious material is a new type of building material,its hydration structure product is similar to ordinary portland cement,but its structure is more dense,with good mechanical properties,short setting time,low resistivity and other characteristics.Alkali activated cementitious materials are generally made of industrial wastes such as slag/fly ash,which are excited by alkali activator made of sodium silicate solution,NaOH and distilled water.Therefore,the alkali activated piezoelectric composite prepared by replacing cement with alkali activated material is a kind of green material with economic and environmental protection,and has good compatibility with concrete materials,which has a good engineering application prospect.In view of this,in this paper,slag/fly ash as the base material,piezoelectric ceramics(PZT)as the functional phase,in the sodium silicate solution,NaOH and distilled water mixed into the alkali activator to form the 0-3 type alkali excited piezoelectric complex,then through the compaction method to improve its compactness,finally in the high-strength electric field,polarization formed with piezoelectric properties of 0-3 type alkali excited Piezoelectric composite material based on hair.In this paper,the piezoelectric and dielectric properties of alkali activated piezoelectric composites were studied by changing the mass ratio of slag to fly ash,different modulus of sodium silicate and different pressing pressure.On this basis,the influence of different volume fraction,different particle size,different gradation of functional phase and polarization condition on the properties of alkali activated piezoelectric composites is further explored.The main results are as follows:Firstly,the effects of the ratio of mineral powder,modulus of sodium silicate and pressing pressure on the dielectric properties and piezoelectric properties of alkali activated matrix piezoelectric composites were preliminarily analyzed by orthogonal experimental method.Then,the influence of the ratio of mineral powder,modulus of sodium silicate and molding pressure on the dielectric properties and piezoelectric properties of alkali activated piezoelectric composites was further explored on the basis of the conclusion obtained from the orthogonal experimental analysis.The experimental results show that the piezoelectric strain constant d33 and piezoelectric voltage constant g33 increase significantly when the ore powder ratio is less than 50%.In addition,the relative permittivity of alkali activated piezoelectric composites is between 30-110,which is consistent with the relative permittivity of cement-based piezoelectric composites in the existing literature.The experimental results show that alkali activated piezoelectric composites can replace cement-based piezoelectric composites.With the increase of pressing pressure,d33 and g33 decreased continuously,and εr and tanσ increased continuously.In conclusion,the piezoelectric and dielectric properties of the piezoelectric composites are better when the ratio of mineral powder is less than 50%,the pressure is 30MPa and the modulus of sodium silicate is 1.0.Based on the above experimental results,the piezoelectric and dielectric properties of PZT with different volume fraction,particle size and gradation were studied by selecting 40%of mineral powder ratio,30MPa of molding pressure and 1.0 of sodium silicate modulus.The effects of polarization process on the piezoelectric and dielectric properties of alkali activated piezoelectric composites were investigated(1)With the increase of PZT volume fraction,the piezoelectric strain constant d33 and the relative dielectric constant εr.The dielectric loss tanσ increases and the piezoelectric voltage constant g33 decreases.Compared with the ordinary cement-based piezoelectric composites with the same PZT volume fraction,it is found that the alkali activated piezoelectric composites have better piezoelectric properties.(2)With the increase of PZT particle size,the piezoelectric strain constant d33 and dielectric loss tanσ increase.It was found that the piezoelectric and dielectric properties were improved when the volume ratio of small PZT was 10%(3)From the analysis of three factors in the process of polarization,polarization temperature and polarization time,the appropriate polarization process parameters for slag/fly ash alkali activated piezoelectric composites are:electric field strength of 2kV/mm-4kv/mm,polarization temperature of 40℃-80℃ and polarization time of 20min.