Disclosure of Invention
Aiming at the problem that the interface bonding integrity and the corrosion resistance of the existing cement-based piezoelectric composite material are poor, the invention provides a method for preparing a material by adopting TiO2/SiO2The method for modifying the surface of piezoelectric ceramics by using composite film adopts TiO2/SiO2The composite film modifies the surface of the piezoelectric ceramic, so that the contact angle of the surface of the piezoelectric ceramic is reduced, the hydrophilicity is improved, the interface bonding is improved due to the existence of Si when the composite film is compounded with cement, and the corrosion resistance of the cement-based piezoelectric composite material is effectively improved due to the existence of Ti, so that the functionality is endowed.
The invention also provides a preparation method of the cement-based piezoelectric composite material, which comprises the step of carrying out TiO treatment on the piezoelectric ceramic2/SiO2Modifying the composite film, and then compounding the modified composite film with cement. The existence of Si and Ti can effectively improve the integrity, interface bonding property and corrosion resistance of the cement-based piezoelectric composite material, and meanwhile, the piezoelectric constant and relative dielectric constant of the piezoelectric ceramic substrate are less in change, the dielectric loss is reduced to some extent, and the normal use of the piezoelectric ceramic is not influenced.
The specific technical scheme of the invention is as follows:
a method for modifying the surface of piezoelectric ceramics comprises the following steps: by using TiO2/SiO2The composite film modifies the surface of the piezoelectric ceramic. Further, the TiO2/SiO2The composite film is covered on the surface of the piezoelectric ceramic so as to increase the compatibility and stability of the piezoelectric ceramic when being subsequently compounded with cement or cement-based composite materials. The cement-based composite material is a composite material containing cement and other components such as polymer and reinforcing fiber.
Aiming at the difference of the structure and the performance of the cement and the piezoelectric ceramic and the problems of long-term durability and stability of the cement-based piezoelectric composite material, the invention adoptsTiO2/SiO2The composite film modifies the surface of the piezoelectric ceramic. TiO 22/SiO2After the composite film is contacted with cement, SiO2Can be mixed with Ca (OH) in cement2C-S-H gel is formed by reaction and forms an organic unified whole with cement, so that the piezoelectric ceramic and the cement are tightly combined, and the interface bonding property and compatibility of the piezoelectric ceramic and the cement are improved; meanwhile, Ti can enter the crystal structure of a reaction product, and the stability and the corrosion resistance of the composite system are improved on a molecular level.
Furthermore, the modification method of the invention has no requirements on the components of the piezoelectric ceramics, and can be suitable for various piezoelectric ceramics, such as one-, two-, three-, four-element piezoelectric ceramics, multi-element piezoelectric ceramics and the like. Among them, the binary system PZT piezoelectric ceramic has a high electromechanical coupling coefficient, a good temperature stability and a high curie temperature (300 ℃), is the most widely used one of the piezoelectric ceramic materials, and has an important practical application value and a potential application prospect, and thus is preferably PZT piezoelectric ceramic. When the PZT piezoelectric ceramic is compounded with cement, it needs to be cut into a desired size and shape according to application conditions and requirements, and in order to better increase the compatibility of the piezoelectric ceramic with cement, it is preferable to cut the piezoelectric ceramic into a shape that can be easily compounded with cement, and then modify it, for example, cut it into a ceramic sheet with a certain size.
Further, the TiO2/SiO2The composite film is coated on the surface of the piezoelectric ceramic in a pulling film forming mode, and the specific modification method comprises the following steps: respectively obtaining TiO by adopting a sol-gel method2Sol and SiO2Sol prepared by mixing TiO with silicon at a molar ratio of titanium to silicon =0.05-0.5:1 (preferably 0.05-0.3: 1)2Sol and SiO2Mixing and stirring the sol uniformly, then adding a silane coupling agent for reaction at 20-40 ℃, and aging at 20-40 ℃ after the reaction to obtain TiO with the pH =1.0-3.02/SiO2Compounding sol; adding TiO into the mixture2/SiO2Uniformly pulling the composite sol on the surface of the piezoelectric ceramic to form a film, and then sintering the piezoelectric ceramic at a low temperature of 80-160 ℃ to obtain TiO2/SiO2Composite film surface modified pressAn electroceramic.
Further, the piezoelectric ceramic is a PZT piezoelectric ceramic sheet.
Further, TiO2/SiO2The composite sol is formed into a film on the surface of the piezoelectric ceramic by a dipping and pulling film-forming method. When dipping and drawing to form a film, the number of the film layers is 2-6, and when preparing the first layer of film, the piezoelectric ceramic is in TiO2/SiO2The dipping time in the composite sol is 1-10min, the pulling speed is 20-60mm/min, and when the other films are prepared, the piezoelectric ceramic is in TiO2/SiO2The dipping time in the composite sol is 1-4min, the pulling speed is 20-60mm/min, and each layer of film is naturally dried for 10 min.
Further, the amount of the silane coupling agent used is 1.5 to 2.5% by mole of silicon. The silane coupling agent can improve TiO2/SiO2The dispersibility and the adhesiveness of the composite sol can also increase the interfacial bondability between the piezoelectric ceramic and the film layer. Examples of the silane coupling agent include KH-570 (methacryloxypropyltrimethoxysilane), A151 (vinyltriethoxysilane), A171 (vinyltrimethoxysilane), and A172 (vinyltris (. beta. -methoxyethoxy) silane), with KH-570 being preferred.
Further, after adding the silane coupling agent, reacting for 1-3h at 20-40 ℃, and aging for 12-36h at 20-40 ℃.
Further, the purpose of low-temperature sintering is to improve TiO2/SiO2The dispersibility of the components in the composite film and the bonding strength of the film and the piezoelectric ceramic. The sintering adopts low-temperature sintering at 80-160 ℃, the heat preservation time is generally 1-3h, the low-temperature sintering can reduce the probability of film cracking and can also avoid the formation of high-temperature sintered crystals from influencing the performance of the piezoelectric ceramics.
Further, the TiO of the present invention2Sol and SiO2The sol can be prepared by the methods disclosed in the prior art, preferably by a sol-gel method, using TBT (tetrabutyl titanate) and TEOS (tetraethyl orthosilicate) as raw materials, and HNO3Hydrolyzing with HCl solution as catalyst and EtOH (ethanol) as solvent to prepare TiO2Sol and SiO2And (3) sol. TiO produced by different methods2Sol and SiO2The sol may have slightly different performance, but the action mechanism of the sol after being contacted with cement is the same, and the aim of the invention can be achieved. In a specific embodiment of the present invention, a more effective TiO is provided2Sol and SiO2The specific preparation method of the sol comprises the following steps: TBT is added into EtOH dropwise according to the molar ratio of EtOH to TBT =0.78:1, and HNO with the concentration of 0.2mol/mL is added dropwise3Stopping dripping when the volume ratio of water to EtOH is 1:1, stirring uniformly after dripping, and aging at 20-35 deg.C for 12-36h to obtain TiO2Sol; mixing EtOH and TEOS according to a molar ratio of 3:1, dropwise adding HCl solution with pH of 2.0 while stirring, stopping dropwise adding when the molar ratio of water to TEOS is 3-5:1, stirring and reacting at 30-50 ℃ for 1-4h, and then aging at 30-50 ℃ for 20-40h to obtain SiO2And (3) sol.
Preferably, the piezoelectric ceramic is pretreated and then TiO is made on the surface of the piezoelectric ceramic2/SiO2And (3) compounding the film. The pretreatment can be the conventional oil and dust removal and cleaning operations of the surface of the piezoelectric ceramic, and can also be further subjected to roughening operations such as grinding, acid etching and the like on the basis of the conventional oil and dust removal and cleaning operations, so that TiO is added2/SiO2The binding force between the composite film and the piezoelectric ceramic.
Further, the piezoelectric ceramic pretreatment mode is as follows: deoiling and cleaning the piezoelectric ceramics, or deoiling and cleaning the piezoelectric ceramics, then sequentially polishing the surfaces by using water-phase abrasive paper and metallographic abrasive paper, and then using HF and HNO3Etching and coarsening the mixed acid solution, and finally cleaning the obtained product. When removing oil, the piezoelectric ceramic can be put into Na2CO3By soaking in solution, Na2CO3The concentration of the solution is preferably 10 to 25 wt%. The HF concentration in the mixed acid is 5-15wt%, HNO3The concentration is 5-15wt%, and the etching time is 10-60 s. The cleaning is carried out by using distilled water, and can be carried out by using distilled water for washing firstly, then carrying out ultrasonic cleaning and finally using distilled water for washing.
Furthermore, the invention also provides a preparation method of the cement/piezoelectric ceramic composite material on the basis of the surface modification methodThe method comprises the following steps: carrying out surface modification on the piezoelectric ceramic according to the method for modifying the surface of the piezoelectric ceramic to obtain TiO2/SiO2Surface modified piezoelectric ceramic of composite film, and then adding TiO2/SiO2And compounding the piezoelectric ceramic with the modified surface of the composite film and cement to obtain the cement/piezoelectric ceramic composite material. The piezoelectric ceramic is firstly subjected to surface modification and then compounded with cement, and when the piezoelectric ceramic is contacted with the cement, TiO on the piezoelectric ceramic is adopted2/SiO2The composite film is in direct contact with the cement, has a calcium-silicon component product similar to the composition of the cement, and can slowly react with SiO in the cement2、Ca(OH)2The components react to form C-S-H gel, Ti also enters into corresponding product crystal lattices and then forms an organic unified whole with cement, so that the piezoelectric ceramic is tightly combined with the cement, and the corrosion resistance and the stability are greatly improved.
Further, in the above method for preparing a cement/piezoelectric ceramic composite material, the piezoelectric ceramic refers to a piezoelectric ceramic of a desired shape and size to be finally compounded with cement. According to actual requirements, the piezoelectric ceramics are firstly cut into required sizes and shapes, and then surface modification is carried out, so that all surfaces in contact with cement are subjected to surface modification.
Furthermore, the invention also provides a cement/piezoelectric ceramic composite material, which is prepared from TiO2/SiO2The piezoelectric ceramic with the modified composite film surface is compounded with cement to obtain the composite film. TiO 22/SiO2The piezoelectric ceramic with the surface modified by the composite film is obtained by processing according to the method for modifying the surface of the piezoelectric ceramic.
The invention selects TiO according to the difference of the structure and the performance of the cement and the piezoelectric ceramic2/SiO2The composite sol is pulled to form a film on the surface of the piezoelectric ceramic, so that uniform and stable TiO is formed on the surface of the piezoelectric ceramic2/SiO2And (3) compounding the film. TiO 22/SiO2After the composite film is contacted with cement, SiO2Can be mixed with Ca (OH) in cement2The C-S-H gel is formed by reaction and is organically integrated with the cement, so that the piezoelectric ceramic and the water are mixedThe mud is tightly combined, so that the interface combination and compatibility of the mud and the mud are improved; meanwhile, Ti can enter the crystal structure of a reaction product, and the stability of the composite system is improved at a molecular level. The existence of Si and Ti can effectively improve the integrity, durability and interface compatibility of the cement-based PZT piezoelectric composite material.
After surface modification, the contact angle of the surface of the piezoelectric ceramic is reduced (less than or equal to 35 degrees), the hydrophilicity is improved, and the binding force is enhanced; meanwhile, the piezoelectric constant and the relative dielectric constant of the piezoelectric ceramic substrate change little (piezoelectric constant d)33The change rate is less than or equal to 2.79 percent, the change rate of the relative dielectric constant is less than or equal to 3.45 percent, the dielectric loss is reduced to a certain extent (the change rate is less than or equal to 2.67 percent), and the normal use of the piezoelectric ceramic is not influenced. On the premise of not influencing the piezoelectric performance of the piezoelectric ceramic, the cement-based piezoelectric composite material has good compatibility with cement and improves the integral bonding property and corrosion resistance of the cement-based piezoelectric composite material.
Detailed Description
The present invention will now be further described with reference to the following examples and accompanying drawings, which are illustrative only and not limiting in their content.
In the following examples, unless otherwise specified, each concentration is a mass percentage concentration.
Example 1
(1) Cutting a prepared PZT piezoelectric ceramic block along the polarization direction by a precision cutting machineForming into flakes of size 22 x 15.6 x 2mm, and adding Na with a pre-prepared concentration of 25wt%2CO3Soaking in the solution for 10min, removing oil, taking out, washing with distilled water, performing ultrasonic treatment at 40 deg.C for 20min, washing with distilled water for three times, and blow-drying;
(2) polishing the degreased PZT piezoelectric ceramic sheets in the step (1) by using 360# water-phase sand paper for 50 circles along the 8 shape, then polishing by using W40 metallographic sand paper for 50 circles along the 8 shape, and then polishing by using PZT piezoelectric ceramic sheets containing 10wt% of HF and 5wt% of HNO3Etching the mixed acid solution for 60s, taking out, ultrasonically cleaning, and blow-drying for later use;
(3) using EtOH and TBT as raw materials, dropwise adding TBT into EtOH under anhydrous condition according to molar ratio n (EtOH)/n (TBT) =0.78 of titanium alkoxide, stirring while dropwise adding, and then dropwise adding HNO of 0.2mol/mL3Controlling the dropping amount of the solution to be 1 in the water-alcohol volume ratio, stirring for 30min after the dropping is finished, and then placing the solution in a drying oven at 25 ℃ for aging for 24h to obtain TiO2Sol;
(4) taking EtOH and TEOS as raw materials, measuring and placing the raw materials in a beaker according to the molar ratio n (EtOH)/n (TEOS) =3 of silicon alcohol and silicon, uniformly mixing the raw materials, dropwise adding an HCl solution with pH =2.0 under magnetic stirring, and controlling the dropwise adding quantity to be the molar ratio n (H) of water and silicon2O)/n (TEOS) =3, sealing the beaker after dripping, stirring for 2h reaction in a water bath kettle at 45 ℃, and then placing in a drying oven at 40 ℃ for aging for 24h to obtain SiO2Sol;
(5) TiO obtained in the step (3) and the step (4)2Sol and SiO2Measuring and mixing sol according to the titanium-silicon molar ratio of 0.1, adding a silane coupling agent KH-570 with the TEOS molar ratio of 2.0% into the mixed sol, magnetically stirring the mixed sol at 30 ℃ for reaction for 2h, controlling the pH value to be 2.0, and aging at 25 ℃ for 36h to obtain TiO2/SiO2Compounding sol;
(6) adopting a film drawing machine to draw the TiO in the step (5)2/SiO2And (3) taking the composite sol as a film-forming solution, and carrying out drawing film formation on the surface of the PZT piezoelectric ceramic sheet obtained by coarsening in the step (2). The number of the film drawing layers is 4, and when the first film is prepared, the coarsened PZT piezoelectric ceramic sheets are in the film-making liquidThe dipping time is 8min, the pulling speed is 30mm/min, the film is naturally dried after being pulled, the drying time is 10min, when the other three layers of films are prepared, the dipping time of the coarsened PZT piezoelectric ceramic sheet in the film-making liquid is 3min, the pulling speed is 30mm/min, the film is naturally dried after being pulled, and the drying time is 10 min;
(7) sintering the PZT piezoelectric ceramic sheet subjected to film drawing in the step (6) at a low temperature of 100 ℃ for 2 hours to obtain the composite material TiO2/SiO2A PZT piezoelectric ceramic sheet with a modified composite film surface.
Example 2
Steps (1) to (4) were the same as in example 1;
(5) TiO obtained in the step (3) and the step (4)2Sol and SiO2Measuring and mixing sol according to the titanium-silicon molar ratio of 0.05, adding a silane coupling agent KH-570 with the TEOS molar ratio of 1.5% into the mixed sol, magnetically stirring the mixed sol at 35 ℃ for reaction for 1h, controlling the pH value to be 1.5, and aging at 30 ℃ for 24h to obtain TiO2/SiO2Compounding sol;
(6) adopting a film drawing machine to draw the TiO in the step (5)2/SiO2And (3) taking the composite sol as a film-forming solution, and carrying out drawing film formation on the surface of the PZT piezoelectric ceramic sheet obtained by coarsening in the step (2). The number of the film drawing layers is 4, when the first layer of film is prepared, the dipping time of the coarsened PZT piezoelectric ceramic sheet in the film making liquid is 8min, the pulling speed is 30mm/min, the film is naturally dried after being drawn, the drying time is 10min, when the other three layers of films are prepared, the dipping time of the coarsened PZT piezoelectric ceramic sheet in the film making liquid is 3min, the pulling speed is 30mm/min, the film is naturally dried after being drawn, and the drying time is 10 min;
(7) sintering the PZT piezoelectric ceramic sheet subjected to film drawing in the step (6) at a low temperature of 80 ℃ for 3 hours to obtain the composite material TiO2/SiO2The PZT piezoelectric ceramic material modified on the surface of the composite film.
Example 3
Steps (1) to (4) were the same as in example 1;
(5) obtained in the step (3) and the step (4)Of TiO 22Sol and SiO2Measuring and mixing sol according to the titanium-silicon molar ratio of 0.2, adding a silane coupling agent KH-570 with the TEOS molar ratio of 2.5% into the mixed sol, magnetically stirring the mixed sol at 35 ℃ for reaction for 1h, controlling the pH value to be 1.0, and aging at 30 ℃ for 36h to obtain TiO2/SiO2Compounding sol;
(6) adopting a film drawing machine to draw the TiO in the step (5)2/SiO2And (3) taking the composite sol as a film-forming solution, and carrying out drawing film formation on the surface of the PZT piezoelectric ceramic sheet obtained by coarsening in the step (2). The number of the film drawing layers is 4, when the first layer of film is prepared, the dipping time of the coarsened PZT piezoelectric ceramic sheet in the film making liquid is 8min, the pulling speed is 30mm/min, the film is naturally dried after being drawn, the drying time is 10min, when the other three layers of films are prepared, the dipping time of the coarsened PZT piezoelectric ceramic sheet in the film making liquid is 3min, the pulling speed is 30mm/min, the film is naturally dried after being drawn, and the drying time is 10 min;
(7) sintering the PZT piezoelectric ceramic sheet subjected to film drawing in the step (6) at a low temperature of 140 ℃ for 2h to obtain the PZT piezoelectric ceramic sheet prepared from TiO2/SiO2The PZT piezoelectric ceramic material modified on the surface of the composite film.
Example 4
Steps (1) to (4) were the same as in example 1;
(5) SiO obtained in the step (3) and the step (4)2Sols and TiO2Measuring and mixing sol according to the titanium-silicon molar ratio of 0.3, adding a silane coupling agent KH-570 with the TEOS molar ratio of 2.0% into the mixed sol, magnetically stirring the mixed sol at 25 ℃ for reacting for 2h, controlling the pH value to be 2.0, and aging at 35 ℃ for 24h to obtain TiO2/SiO2Compounding sol;
(6) adopting a film drawing machine to draw the TiO in the step (5)2/SiO2And (3) taking the composite sol as a film-forming solution, and carrying out drawing film formation on the surface of the PZT piezoelectric ceramic sheet obtained by coarsening in the step (2). The number of the film drawing layers is 4, when the first layer of film is prepared, the immersion time of the coarsened PZT piezoelectric ceramic sheet in the film preparation liquid is 8min, the drawing speed is 30mm/min, and the film drawing is performedNaturally drying, wherein the drying time is 10min, when the other three layers of films are prepared, the immersion time of the coarsened PZT piezoelectric ceramic sheet in the film-making liquid is 3min, the pulling speed is 30mm/min, and the film is naturally dried after being pulled, and the drying time is 10 min;
(7) sintering the PZT piezoelectric ceramic sheet subjected to film drawing in the step (6) at a low temperature of 160 ℃ for 1h to obtain the PZT piezoelectric ceramic sheet prepared from TiO2/SiO2The PZT piezoelectric ceramic material modified on the surface of the composite film.
Example 5
Steps (1) to (4) were the same as in example 1;
(5) SiO obtained in the step (3) and the step (4)2Sols and TiO2Measuring and mixing sol according to the titanium-silicon molar ratio of 0.3, adding a silane coupling agent KH-570 with the TEOS molar ratio of 2.5% into the mixed sol, magnetically stirring the mixed sol at 25 ℃ for reacting for 2h, controlling the pH value to be 2.0, and aging at 35 ℃ for 24h to obtain TiO2/SiO2Compounding sol;
(6) adopting a film drawing machine to draw the TiO in the step (5)2/SiO2And (3) taking the composite sol as a film-forming solution, and carrying out drawing film formation on the surface of the PZT piezoelectric ceramic sheet obtained by coarsening in the step (2). The number of the film drawing layers is 4, when the first layer of film is prepared, the dipping time of the coarsened PZT piezoelectric ceramic sheet in the film making liquid is 8min, the pulling speed is 30mm/min, the film is naturally dried after being drawn, the drying time is 10min, when the other three layers of films are prepared, the dipping time of the coarsened PZT piezoelectric ceramic sheet in the film making liquid is 3min, the pulling speed is 30mm/min, the film is naturally dried after being drawn, and the drying time is 10 min;
(7) sintering the PZT piezoelectric ceramic sheet subjected to film drawing in the step (6) at a low temperature of 120 ℃ for 2h to obtain the PZT piezoelectric ceramic sheet prepared from TiO2/SiO2The PZT piezoelectric ceramic material modified on the surface of the composite film.
Example 6
Steps (1) to (4) were the same as in example 1;
(5) TiO obtained in the step (3) and the step (4)2Sol and SiO2Sol of titaniumMeasuring and mixing the mixture with the silicon molar ratio of 0.2, adding a silane coupling agent KH-570 with the TEOS molar weight of 1.5% into the mixed sol, magnetically stirring the mixed sol at 35 ℃ for reaction for 1h, controlling the pH value to be 1.0, and aging at 30 ℃ for 36h to obtain TiO2/SiO2Compounding sol;
(6) adopting a film drawing machine to draw the TiO in the step (5)2/SiO2And (3) taking the composite sol as a film-forming solution, and carrying out drawing film formation on the surface of the PZT piezoelectric ceramic sheet obtained by coarsening in the step (2). The number of the film drawing layers is 4, when the first layer of film is prepared, the dipping time of the coarsened PZT piezoelectric ceramic sheet in the film making liquid is 8min, the pulling speed is 30mm/min, the film is naturally dried after being drawn, the drying time is 10min, when the other three layers of films are prepared, the dipping time of the coarsened PZT piezoelectric ceramic sheet in the film making liquid is 3min, the pulling speed is 30mm/min, the film is naturally dried after being drawn, and the drying time is 10 min;
(7) sintering the PZT piezoelectric ceramic sheet subjected to film drawing in the step (6) at a low temperature of 80 ℃ for 3h to obtain the PZT piezoelectric ceramic sheet prepared from TiO2/SiO2The PZT piezoelectric ceramic material modified on the surface of the composite film.
Comparative example 1
Steps (1) to (2) were the same as in example 1;
(3) and (3) sintering the PZT piezoelectric ceramic sheets in the step (2) at a low temperature of 100 ℃ for 2 h.
Comparative example 2
Steps (1) to (2) were the same as in example 1;
(3) same as in step (4) of example 1, except that: adding a silane coupling agent KH-570 with the TEOS molar weight of 2.0% before aging, and uniformly stirring;
(4) adopting a film drawing machine to draw the SiO in the step (3)2And (3) taking the sol as a film-forming solution, and carrying out drawing film formation on the surface of the PZT piezoelectric ceramic sheet obtained by coarsening in the step (2). The number of the film drawing layers is 4, when the first layer of film is prepared, the immersion time of the coarsened PZT piezoelectric ceramic sheet in the film making liquid is 8min, the drawing speed is 30mm/min, the film is naturally dried after being drawn, the drying time is 10min, when the other three layers of films are prepared, the coarsening is carried outThe immersion time of the PZT piezoelectric ceramic sheets in the membrane preparation liquid is 3min, the pulling speed is 30mm/min, and the PZT piezoelectric ceramic sheets are naturally dried after membrane pulling for 10 min;
(5) sintering the PZT piezoelectric ceramic sheets subjected to film drawing in the step (4) at a low temperature of 100 ℃ for 2 hours to obtain the product made of SiO2The film surface modified PZT piezoelectric ceramic material.
Comparative example 3
Steps (1) to (3) were the same as in example 1;
(4) same as in step (4) of example 1, except that: adding a silane coupling agent KH-570 with the TEOS molar weight of 2.0% before aging, and uniformly stirring;
(5) adopting a film drawing machine to respectively use SiO in the steps (4) and (3)2Sols and TiO2And (3) taking the sol as a film-forming solution, and sequentially carrying out pulling film formation on the surface of the PZT piezoelectric ceramic sheet obtained by coarsening in the step (2). Using SiO first2Sol, reuse of TiO2Sol, wherein the number of layers of two sol drawing films is 2 respectively, when the first layer of film is prepared, the dipping time of the coarsened PZT piezoelectric ceramic sheet in the film-forming liquid is 8min, the pulling speed is 30mm/min, the film is naturally dried after drawing, the drying time is 10min, when the other three layers of films are prepared, the dipping time of the coarsened PZT piezoelectric ceramic sheet in the film-forming liquid is 3min, the pulling speed is 30mm/min, the film is naturally dried after drawing, and the drying time is 10 min;
(6) sintering the PZT piezoelectric ceramic sheets subjected to film drawing in the step (4) at a low temperature of 100 ℃ for 2 hours to obtain the product made of SiO2Film and TiO2Film-laminated surface-modified PZT piezoceramic material.
Comparative example 4
A piezoelectric ceramic sheet was surface-modified in the same manner as in example 1, except that TiO was used2/SiO2No silane coupling agent KH-570 is added into the composite sol.
Comparative example 5
The surface modification of the piezoelectric ceramic sheet was carried out by the method of example 1, except that the PZT piezoelectric ceramic sheet after the film drawing in the step (5) was sintered at 260 ℃ for 2 hours.
Comparative example 6
Steps (1) to (3) were the same as in example 1;
(4) adopting a film drawing machine to draw the TiO in the step (3)2And (3) taking the sol as a film-forming solution, and carrying out drawing film formation on the surface of the PZT piezoelectric ceramic sheet obtained by coarsening in the step (2). The number of the film drawing layers is 4, when the first layer of film is prepared, the dipping time of the coarsened PZT piezoelectric ceramic sheet in the film making liquid is 8min, the pulling speed is 30mm/min, the film is naturally dried after being drawn, the drying time is 10min, when the other three layers of films are prepared, the dipping time of the coarsened PZT piezoelectric ceramic sheet in the film making liquid is 3min, the pulling speed is 30mm/min, the film is naturally dried after being drawn, and the drying time is 10 min;
(5) sintering the PZT piezoelectric ceramic sheet subjected to film drawing in the step (4) at a low temperature of 100 ℃ for 2 hours to obtain the PZT piezoelectric ceramic sheet prepared from TiO2The film surface modified PZT piezoelectric ceramic material.
For TiO in example 12/SiO2Composite sol and SiO in comparative example 22Drying and grinding the sol, and then carrying out XRD detection to obtain an XRD pattern as shown in figure 1, wherein 25 degrees corresponds to SiO2The peak of the precursor is about 43 degrees, which is a newly generated peak after Ti is introduced, and the Ti is successfully introduced into the composite film; and the shape of the diffraction peaks indicates that the powder is mainly in an amorphous state, which is also the reason for the subsequent low temperature sintering.
SEM characterization of the modified PZT piezoelectric ceramic sheets of example 1 and comparative example 2 is shown in FIG. 2, from which it can be seen that pure SiO2When the film is covered on the surface of the piezoelectric ceramic, the film is thicker, the appearance of particles on the surface of the piezoelectric ceramic is covered, a small amount of cracks are generated due to the shrinkage of the film, and SiO is generated2/TiO2Composite film and pure SiO2Compared with the film, the film uniformly covers the surface of the piezoelectric substrate, is more compact, has less cracks, retains the basic texture of the piezoelectric ceramic of the substrate, increases the interface bonding force, and can effectively improve the interface bonding property while leveling by introducing Ti. PZT piezoelectrics after modification treatment of example 1 and comparative example 2The change in contact angle of the ceramic flakes is shown in FIG. 3, which is evident from the SiO transition2/TiO2The contact angle of the surface of the piezoelectric ceramic after the surface modification of the composite film is reduced, the wettability is better, and the SiO is proved2/TiO2The composite film is more beneficial to the combination of the piezoelectric ceramics and the cement-based material.
The results of the tests on the wetting of the PZT piezoelectric ceramic sheets after the modification treatments of example 1, comparative example 1 and comparative example 2 are shown in FIG. 4, from which it can be seen that SiO according to the present invention is used2/TiO2The hydrophilicity of the composite film is obviously higher than that of pure SiO2The membrane has good hydrophilicity.
Comparing the surface films of example 1 and comparative example 4, it can be seen that the surface film of example 1 has a greater thickness than the surface film of comparative example 4, and the surface film of example 1 is more uniform and free from cracks, and the film of comparative example 4 has a phenomenon of cracks. Therefore, KH-570 can be added to reduce the agglomeration of colloidal particles, so that the colloidal particles are uniformly dispersed, the problem of film cracking is solved, and the bonding force between the film and the piezoelectric ceramic matrix is increased; meanwhile, the KH-570 can slightly increase the contact angle of the modified piezoelectric ceramic, so the addition amount of the KH-570 is controlled to achieve the purposes of improving the uniformity of the membrane, increasing the interface bonding force and not greatly losing the hydrophilicity of the membrane layer.
The PZT piezoelectric ceramic materials obtained in comparative example 2, comparative example 3, comparative example 6, and example 1 were put into a 3.5wt% NaCl solution and corroded for 72 hours, and the results showed that: SiO of comparative example 22Film cracking was evident, TiO of comparative example 62Thin film layer, SiO of comparative example 32Film and TiO2The film-laminated composite film was not uniform and had breakage, whereas SiO of example 12/TiO2The composite film has no obvious change before and after corrosion, which shows that the composite film has obvious corrosion resistance and achieves the aim of modification; in addition, the hydrophilicity of the PZT piezoelectric ceramics modified by the first three films is also higher than that of SiO2/TiO2Poor after modification of the composite film, thus SiO2/TiO2The composite film integrates SiO2With TiO2The two films have the advantages of good performance, good performance and good performanceThe aim of modifying the PZT piezoelectric ceramic interface is achieved.
Each of the modified PZT piezoelectric ceramic sheets prepared in the above examples and comparative examples was subjected to a performance test, and its surface contact angle, quasi-static d, was measured using a contact angle measuring instrument33The measuring instrument measures the piezoelectric constant d33The impedance analyzer measures and calculates the relative dielectric constant and dielectric loss thereof, and the results are shown in table 1 below.
Piezoelectric constant d of each PZT piezoelectric ceramic sheet obtained in the above examples and comparative examples33The changes in relative dielectric constant and dielectric loss compared to the corresponding properties of comparative example 1 are summarized as shown in table 2 below.
As can be seen from tables 1 and 2, PZT piezoelectric ceramic sheets were subjected to TiO deposition of the present invention2/SiO2The contact angle of the modified composite film surface is obviously reduced (less than or equal to 35 degrees), the piezoelectric property of the piezoelectric ceramic substrate is almost unchanged, and the relative dielectric constant and the dielectric loss change are small (the piezoelectric constant d is small)33The change rate is less than or equal to 2.79 percent, the change rate of the relative dielectric constant is less than or equal to 3.45 percent, the change rate of the dielectric loss is less than or equal to 2.67 percent), the normal use of the piezoelectric ceramic is not influenced, and the aims of ensuring that the PZT piezoelectric ceramic has good compatibility with cement on the premise of not influencing the piezoelectric performance of the PZT piezoelectric ceramic and improving the integrity, stability and corrosion resistance of the cement-based PZT piezoelectric composite material are achieved. In addition, with pure SiO2Compared with PZT piezoelectric ceramics with modified film surface, the TiO of the invention2/SiO2Piezoelectric constant d of PZT piezoelectric ceramic modified by composite film33And the relative dielectric constant and the dielectric loss are less in change, so that the method has obvious advantages.