The present invention relates to a concrete composite comprising concrete and a thermoelectric material, wherein the thermoelectric material comprises a complex sulphide mineral, wherein the composite comprises at least 20 wt % concrete.

Provided are a method for preparing a gel composite material with a piezoelectric property, and the gel composite material and use thereof, which belongs to the field of intelligent road traffic. In the method, titanium-containing blast furnace slag and metal oxides (PbO and ZrO.sub.2) are sufficiently and uniformly mixed, an obtained mixture is calcined under a certain thermal system, on the theoretical basis of mineral-phase reconstruction-synergistic regulation of all valuable components, and the mixture is cooled to a room temperature with a furnace to obtain the gel composite material with a piezoelectric property.

A coating process comprising applying to a surface a coating composition consisting essentially of an alkali metal silicate and an aqueous liquid phase having dispersed therein solid aluminum particles to form on the surface a wet coating; and drying said wet coating: under conditions which convert said wet coating to an electrically conductive, corrosion-resistant, solid coating; or under conditions which form a solid coating which is not electrically conductive (non-conductive) and thereafter treating said non-conductive coating under conditions which convert said non-conductive coating to an electrically conductive, corrosion-resistant coating.

Provided is a dielectric composition exhibiting a high strength and a high specific dielectric constant. The dielectric composition contains composite oxide particles having a composition formula represented by (Sr.sub.xBa.sub.1-x).sub.yNb.sub.2O.sub.5+y and an Al-based segregation phase. The Al segregation phase has niobium, aluminum, and oxygen.

An LTCC microwave dielectric material, including the following components: a Ba.sub.5Si.sub.8O.sub.21+(1−a) (Mg.sub.xCa.sub.ySr.sub.zBa.sub.1-x-y-z)WO.sub.4+Ba—B—Si glass; wherein 0.4≤a≤0.8, 0≤x≤1, 0≤y≤1, 0≤z≤1. By adjusting the amounts of Ba.sub.5Si.sub.8O.sub.21 and (Mg.sub.xCa.sub.ySr.sub.zBa.sub.1-x-y-z)WO.sub.4, the temperature coefficient of resonance frequency can be adjusted to nearly zero. The material is suitable for the fields of high-frequency communication and radiofrequency. Also disclosed is a method for preparing the LTCC microwave dielectric material.

Provided is a dielectric composition exhibiting a high strength and a high specific dielectric constant. The dielectric composition contains composite oxide particles having a composition formula represented by (Sr.sub.xBa.sub.1-x).sub.yNb.sub.2O.sub.5+y and an Al-based segregation phase. The Al segregation phase has niobium, aluminum, and oxygen.

A hydrophobic dielectric sealing material is provided that is especially suitable for use in extreme environments such as for enabling downhole electrical feedthrough integrated logging tools reliable operation, especially, in a water or water-mud filled wellbore as first scenario or in moisture-rich oil-mud filled wellbores. In some embodiments, a hydrophobic dielectric sealing material may include: H.sub.3BO.sub.3 10-60 mol %; Bi.sub.2O.sub.3 10-50 mol %; MO 10-50 mol %; SiO.sub.2 0-15 mol %; and optionally one or more rare earth oxides 0-5 mol %. A method for making hydrophobic sealing material includes selecting water insoluble raw materials, form tetragonal phase dominated phase, and enlarge band-gap with wide-band-gap material. The morphology of the sealing material is preferably a tetrahedral phase dominated covalent bond network for obtaining high electrical insulation resistance, dielectric strength and hydrophobicity, and high mechanical strength in against downhole 30,000 PSI/300 C. water-based hostile environments.

An oil-gas well, a well cementation method, and a cement composition are provided. The oil-gas well has a well body, a sleeve disposed in the well body, and a cement slurry cured product disposed between the well body and the sleeve. Due to the strength and toughness of the cement slurry cured product, at least part of the sleeve is a non-metal sleeve. By selecting specific cement, the cured product of cement has excellent mechanical strength and toughness, and is mated with the non-metal sleeve to achieve well cementation.

The present invention relates to a process for preparing a humidity sensor based on resistive type porous Magnesium Ferrite (MgFe.sub.2O.sub.4) pellets and a humidity sensor thereof. More particularly, the present invention includes a synthesis process of preparing 30 to 40% porous MgFe.sub.2O.sub.4 pellets. The process further includes making Ohmic contacts on the porous MgFe.sub.2O.sub.4 pellets. The process is very cost effective and optimized to keep the resistance of the porous MgFe.sub.2O.sub.4 pellets in the range 200-300 M. Further, the response and recovery time of the porous MgFe.sub.2O.sub.4 pellets to humidity is in the range of few seconds only. Further, the porous MgFe.sub.2O.sub.4 pellets can be used for humidity sensing for more than 12 months. Due to resistance stability even after long-term exposure in humidity, the porous MgFe.sub.2O.sub.4 pellets do not require flash heating. Further, the humidity sensor prepared according to the process is highly sensitive towards relative humidity changes as the same is based on the measurement of resistance changes as compared to known humidity sensors which are based on the measurement of capacitance changes.

An LTCC microwave dielectric material, including the following components: a Ba.sub.5Si.sub.8O.sub.21+(1a) (Mg.sub.xCa.sub.ySr.sub.zBa.sub.1-x-y-z)WO.sub.4+BaBSi glass; wherein 0.4a0.8, 0x1, 0y1, 0z1. By adjusting the amounts of Ba.sub.5Si.sub.8O.sub.21 and (Mg.sub.xCa.sub.ySr.sub.zBa.sub.1-x-y-z)WO.sub.4, the temperature coefficient of resonance frequency can be adjusted to nearly zero. The material is suitable for the fields of high-frequency communication and radiofrequency. Also disclosed is a method for preparing the LTCC microwave dielectric material.