75results about How to "Improve sintering properties" patented technology

The invention discloses a low temperature sintering piezoelectric ceramic material, wherein composition of the material is represented by a chemical general formula Pb(0.995-a-b-3c / 2)BaaSrbFec(Zn1 / 3Nb2 / 3)xZryTi(1-x-y)O3+u%Li2CO3+v%M2O3+w%ZnO, M is a trivalent metal element, a molar ratio of Ba to Sr to Fe to (Zn1 / 3Nb2 / 3) to Zr is a:b:c:x:y, a is more than or equal to 0 and is less than or equal to 0.05, b is more than or equal to 0 and is less than or equal to 0.03, c is more than or equal to 0 and is less than or equal to 0.01, x is more than or equal to 0.25 and is less than or equal to 0.35, y is more than or equal to 0.30 and is less than or equal to 0.40, the Pb(0.995-a-b-3c / 2)BaaSrbFec(Zn1 / 3Nb2 / 3)xZryTi(1-x-y)O3 is adopted as matrix ceramic powder, u% represents a weight percentage of Li2CO3 in the matrix ceramic powder, v% represents a weight percentage of M2O3 in the matrix ceramic powder, w% represents a weight percentage of ZnO in the matrix ceramic powder, u is more than 0 and is less than or equal to 1, v is more than 0 and is less than or equal to 2, and w is more than 0 and is less than or equal to 0.2. According to the present invention, an oxide dopant is added and combined, such that a sintering temperature of the ceramic can be reduced to a temperature of 900 DEG C from a temperature of 1200 DEG C, a high piezoelectric constant (d33 is more than or equal to 450 pC / N ), a high electromechanical coupling coefficient (KP is more than or equal to 0.60), a high Curie point (Tc is more than 350 DEG C) and a moderate dielectric constant (epsilonr is 2000-3500) can be obtained, and application requirements on the ceramic material by the laminated piezoelectric driver are met.

The invention discloses a method for preparing magnesium tantalate microwave ceramic powder by a sol-gel technique, which comprises the following steps of: (1) preparing citric acid aqueous solution of tantalum, wherein the mol ratio of citric acid to tantalum ions is 2:1-6:1; (2) preparing citric acid aqueous solution of magnesium, wherein the mol ratio of the citric acid to magnesium nitrate is 5:1-10:1, and the pH value is 3 to 5; and (3) preparing solution of Mg-Ta precursor, xerogel and nano powder. The method overcomes the defects that the current solid phase method for synthesizing the magnesium tantalate microwave ceramic powder has high synthesis temperature, large particle size, impure phase and the like; and the method prepares high-purity magnesium tantalate microwave ceramic powder with the average particle size of 40 to 80 nanometers.

The invention discloses a method for preparing magnesium niobate microwave ceramic powder through a sol-gel technology. The method comprises the following steps: (1), preparing a citric acid aqueous solution for niobium; (2), preparing a citric acid aqueous solution for magnesium; (3), obtaining a Mg-Nb precursor solution, xerogel and nano-powder. According to the invention, the defects that the magnesium niobate microwave ceramic powder synthesized through a solid phase method at present is high in temperature and large in particle size are overcome, and the magnesium niobate microwave ceramic powder, of which the average particle size is 40-80 nm, is prepared under the condition that the calcination temperature is 550-850 DEG C.

The invention relates to a modified potassium-sodium niobate based leadless piezoelectric ceramics substituted by bismuth ion and a preparation method thereof; the raw materials includes anhydrous potassium carbonate, anhydrous sodium carbonate, niobium pentaoxide and dibismuth trioxide; the stoichiometric ratio thereof is ((K0.5Na0.5)1-3xBix)NbO3(x is more than or equal to 0.0 and less than or equal to 0.05), wherein, x is more than or equal to 0.0 and less than or equal to 0.5; the bismuth ion is added to replace the ion at A position in (K0.5Na0.5)NbO3 ceramics, thus improving sintering characteristics and ferroelectric properties of potassium-sodium niobate ceramics and further enhancing piezoelectric properties thereof. During preparation, according to the principle of electrical valence equilibrium, the bismuth ion is added and K ion and Na ion are reduced at the same time, thus generating the vacancy at the A position and avoiding the formation of residual matter; therefore, the piezoelectric properties d33 and kp can reach 164pC / N and 47% respectively; moreover, the invention is characterized by broad source of the raw materials, good stability of the technique and no environment pollution.

The invention belongs to the field of piezoelectric ceramic materials, and particularly relates to a preparation method of bismuth ferrite-lead titanate-bismuth magnesium niobate ternary system high-temperature piezoelectric ceramic. The chemical formula is (1-x-y) BiFeO3-xPbTiO3-yBi (Mg2 / 3Nb1 / 3) O3, x and y are molar weights, and x is more than or equal to 0.20 and less than or equal to 0.40; 0.01 < = y < = 0.10; the auxiliary component is mBi2O3 + nPbO + zMnO, m, n and z are the mass percent of the total formula, and m is larger than or equal to 0 and smaller than or equal to 0.10; 0 < = n < = 0.10; 0 < = z < = 0.10. The preparation method comprises the following steps: S1, weighing the raw materials; s2, carrying out primary ball milling; step S3: drying; s4, performing solid-phase synthesis; step S5, carrying out secondary ball milling; step S6, granulating and forming; step S7, glue discharging; step S8; and step S9. The sintering temperature of a system can be reduced, ceramic densification is promoted, cracking and pulverization are avoided, the ceramic has the good sintering characteristic, the c / a ratio of the system is reduced, the material is easy to polarize, the ceramic obtains the large piezoelectric coefficient under the condition that the high Curie temperature is guaranteed, the insulativity and temperature stability of the material are improved, and the service life of the material is prolonged. And practical application of devices at high temperature is facilitated.

The invention discloses a wear-resistant ceramic for daily use and a preparation method thereof. The wear-resistant daily-use ceramics include a daily-use ceramic body and a glaze layer, and the glaze layer is made of the following raw materials in parts by weight: 30-40 parts of zircon sand, 10-15 parts of baddeleyite, and 5-10 parts of syenite, 3-6 parts of titanium carbide powder, 3-5 parts of titanium dioxide, 4-6 parts of lutetium oxide, 2-4 parts of tungsten powder, 2-4 parts of polyvinyl alcohol with a mass fraction of 5wt% 2-4 parts of glycerin, 20-30 parts of water. The wear-resistant daily-use ceramics of the present invention are obtained through synergistic cooperation of components, and the obtained wear-resistant daily-use ceramics have a smooth glazed surface, good texture, excellent hardness and bending strength, and excellent wear resistance.

The invention discloses a preparation method of a Sr, Ni and Cr co-doped LaAlO3 ceramic material and a product thereof. According to the stoichiometric ratio of the chemical formula of LaaSrbNicAldCreO3, the chemical formula of LaaSrbNicAldCreO3 is as shown in the specification, wherein a=0.7-0.9; b = 0.05-0.15, c = 0.05-0.15, d = 0.7-0.9, e=0.1-0. 3, weighing strontium nitrate, nickel nitrate, chromium nitrate, lanthanum nitrate and aluminum nitrate; soluble in water, then adding a certain amount of urea, performing ultrasonic dispersion and microwave heating, drying and roasting, grinding and compression molding, calcining for a period of time to obtain the product, the product is good in compactness and excellent in radiation performance, the infrared emissivity of the product at 0.76-2.5 microns is 0.95-0.97, the thermal conductivity of the product at the temperature of 1200 DEG C is 1.986-2.103 W.m <-1 >. K <-1 >, and the forbidden band width of the product is 1.31-1.35 eV.

The invention belongs to the technical field of preparation and application of ceramics, and particularly relates to a method for preparing NdNbO4 microwave dielectric ceramic by utilizing a wet chemical process. The technical scheme is as follows: the method for preparing the NdNbO4 microwave dielectric ceramic by utilizing the wet chemical process comprises the following steps: (1) preparing a citric acid water solution of Nd ions; (2) preparing a citric acid water solution of Nb ions; (3) synthesizing a NdNbO4 microwave dielectric ceramic nanometer precursor and preparing the ceramic. The method has the remarkable advantages that the synthetic temperature is low, ceramic particles are uniform, the dispersity is good, the phase is pure, and the powder body has a nanometer particle size (which is about 50 nanometers), also has high specific surface energy and has relatively high activity, and the like. In comparison with a conventional solid phase method, the method disclosed by the invention can be used for reducing the sintering temperature by 100 to 200 DEG C, realizing intermediate and low-temperature sintering and also retaining good microwave dielectric performance of the ceramic, and is expected to meet the LTCC application requirements.

The invention is to provide a liquid crystal aligning agent for a liquid crystal display device to obtain a liquid crystal alignment layer having excellent burning characteristics even when not only an ITO but a reflective electrode is used, and to provide a liquid crystal display device having a liquid crystal alignment layer obtained from the agent. The liquid crystal aligning agent comprises 100 parts by weight of a polymer having an amic acid repeating unit and an imide repeating unit, with the proportion of the amic acid repeating unit by 40 to 60% by weight in the entire repeating units, and at least 5 parts by weight of a compound having at least two epoxy groups in the molecule.