pressure transmitter is a device that converts pressure into a pneumatic signal or an electric signal for control and remote transmission. Pressure Sensor can convert the physical pressure parameters such as gas and liquid felt by the load cell sensor into a standard electrical signal (such as 4~20mADC, etc.), to supply secondary instruments such as indicating alarms, recorders, regulators, etc. for measurement and indication and process regulation.
Pressure transmitters are used in various industrial automatic control environments, involving water conservancy and hydropower, railway transportation, intelligent buildings, production automatic control, aerospace, military industry, petrochemical, oil wells, electric power, ships, machine tools, pipelines and many other industries.
There are two types of pressure transmitters: electric and pneumatic. The uniform output signal of the electric type is a direct current signal such as 0-10mA, 4-20mA or 1-5V. The unified output signal of the pneumatic type is the gas pressure of 20-100Pa.
Pressure transmitters can be divided into force (torque) balance type, capacitive type, inductive type, strain type and frequency type according to different conversion principles.
Our advantageous products are mainly compact pressure transmitters, pressure transmitters with display, differential pressure transmitters, wind pressure transmitters, etc.
The main advantage
1. The pressure transmitter has the characteristics of reliable operation and stable performance
2. Dedicated V/I integrated circuit, less peripheral components, high reliability, simple and easy maintenance, small size, light weight, and extremely convenient installation and debugging;
3. Aluminum alloy die-casting shell, three-terminal isolation, electrostatic spray protection layer, durable;
4. 4-20mA DC two-wire signal transmission, strong anti-interference ability and long transmission distance;
5. LED, LCD, and pointer three kinds of indicator heads, the on-site reading is very convenient. Can be used to measure viscous, crystalline and corrosive media;
6. High accuracy and high stability. In addition to the imported original sensor that has been corrected by laser, the comprehensive temperature drift and nonlinearity of the whole machine within the operating temperature range are finely compensated.
Pressure Transmitter,Pressure Transducer Sensor,Digital Pressure Sensor,Pressure Transmitter 4-20Ma Wuxi Winsun Automation Instrument Co., Ltd , https://www.winsunwx.com
In view of the important basic position and role of materials, every spurt of science and technology has put forward higher and higher, more stringent and more and more requirements for the performance of materials. Nowadays, in many respects, traditional single materials can no longer meet the actual needs. In this case, people use their intelligent minds to extend the new development direction of materials to a broader field - composite materials.
In this paper, the basic concepts of composite materials, theoretical problems in processing, preparation techniques and methods, and typical applications will be elaborated. It is hoped that a comprehensive introduction to composite materials can be made.
First let's give a clear definition of the composite. According to the International Organization for Standardization (ISO) for the definition of composite materials, a composite material (Compose Material) is a multiphase solid material composed of two or more substances with different physical and chemical properties. . Although the composite material of the composite material maintains its relative independence, the performance of the composite material is not a simple sum of the properties of the component materials, but an important improvement. In a composite material, one phase is usually a continuous phase (referred to as a matrix) and the other phase is a dispersed phase (reinforcing material). The dispersed phase is distributed in an independent form throughout the continuous phase. There is a phase interface between the two phases, and the dispersed phase may be a reinforcing fiber or a granular or dispersed filler.
The emergence and development of composite materials is the result of continuous advancement in modern science and technology and a breakthrough in material design. It combines the advantages of various materials such as fiber, resin, rubber, metal, ceramics, etc., designed according to needs, and composited into a new type of material with excellent comprehensive performance. It can be foreseen that if materials are used as the basis for historical staging, then, in the age of stone, bronze, iron, and steel, in the century, it will be the era of composite materials.
In the rest of the overview, let's take a look at some of the basics of composites.
I. Naming and classification of composite materials Composite materials can be named according to the names of reinforcing materials and matrix materials. Put the name of the reinforcement in front, the name of the base material on the back, and the name "material". For ease of writing, you can also write only the abbreviated names of the reinforcing material and the base material, separated by a diagonal line, followed by "composite material". Sometimes, in order to highlight the reinforcing material or the base material, parts that are not emphasized may be omitted or abbreviated depending on the components to be emphasized.
There are many methods for classifying composite materials. The common classification methods are as follows:
a. According to the shape of the reinforcing material: continuous fiber composite material, short fiber composite material, granular filler composite material, braided composite material b. Classification by reinforcing fiber type: glass fiber composite material, carbon fiber composite material, organic fiber composite material, metal fiber Composite materials, ceramic fiber composites, hybrid composites (composites of composite materials)
c. Classification by matrix material: polymer matrix composite, metal matrix composite, inorganic non-metal matrix composite d. Classification by material: structural composite, functional composite
Second, the basic properties of composite materials:
Composite materials are composited from multiphase materials and their common features are:
(1) Comprehensively exert the advantages of various constituent materials, so that one material has various properties and has properties not possessed by natural materials. (2) Materials can be designed and manufactured according to the needs of material properties (3) The required shape of the product can avoid multiple processing steps. Because the performance of the composite material is affected by many factors, the performance of different composite materials is different, that is, the performance of the same type of composite material is not a fixed value, so here is given Some main features:
I Polymer-based composites i) Specific strength, specific modulus, ii) Good fatigue resistance, iii) Good shock absorption iv) Good safety performance under overload. v) Multi-functionality, ablation resistance, good friction performance (vi) Good processing technology II Metal matrix composites i) High specific strength, high specific modulus ii) High thermal conductivity and high electrical conductivity. iii ) small coefficient of thermal expansion, iv) good dimensional stability, good high temperature performance v) good wear resistance. vi) good fatigue resistance and fracture toughness vii) no moisture absorption, no aging, good air tightness III ceramic matrix composite i) high strength, high hardness, ii) high temperature resistance, oxidation resistance, good abrasion resistance at high temperature, excellent chemical resistance, iii) small coefficient of thermal expansion and specific gravity, iv) high flexural strength after composite material is made, High fracture toughness IV Cement-based composites:
i) high compressive strength i) excellent thermal performance, ii) enhanced tensile and corrosion resistance after composites, weight reduction. Through some of the above descriptions, we have a preliminary understanding of some fundamental points of composite materials. Now let's get to the point and discuss some of the manufacturing process of composite materials.
Chapter II Theoretical Problems in Processing
First, the choice of matrix and reinforcement materials Due to the difference in matrix materials, we need to separate these materials. First, let's look at the matrix selection of metal matrix composites. The performance requirements of metal matrix composites (zero) are the most important basis for selecting metal matrix materials. There are significant differences in the performance requirements of composite components in different technical fields and under different operating conditions. Different composite substrates should be selected according to different situations. High specific strength, specific modulus, and dimensional stability are the most important performance requirements in aerospace and aerospace technologies. A light metal alloy having a small density should be used as the substrate. High-performance engines require composite materials not only with high specific strength and specific modulus properties, but also require composite materials with excellent high temperature resistance, and can work normally in high temperature and oxidizing atmospheres. Titanium-based and nickel-based alloys are required. Intermetallic compounds are used as matrix materials. Automobile engines require heat-resistant, wear-resistant, heat-conducting, high-temperature strength, etc., while requiring low cost. For mass production, aluminum alloy is used as the base material. Industrial integrated circuits require high thermal conductivity, low expansion metal matrix composites as heat sink components and substrates. Metals such as Ag, Cu, and Al having high thermal conductivity are selected as the matrix.
Due to the nature of the reinforcement and the mechanism of reinforcement, there are significant differences in the choice of matrix materials. For continuous fiber reinforced metal matrix composites, the fiber is the main load-bearing object, which itself has high strength and modulus, while the strength and modulus of the metal matrix are far lower than the fiber properties, so in the continuous fiber reinforced metal matrix composite The main role of the matrix in the material should be to give full play to the properties of the reinforcing fiber. The matrix itself should have good compatibility and plasticity with the fiber, and the matrix itself is not required to have high strength. However, for non-continuously enhanced (particle, whisker, short fiber) metal matrix composites, the matrix is ​​the main carrier and its strength has a decisive influence on the discontinuously reinforced metal matrix composite. Therefore, in order to obtain high-performance metal-based composite materials, high-strength aluminum alloys must be used as the matrix, which is completely different from the selection of continuous fiber-reinforced metal matrix composite substrates.
When selecting the substrate, sufficient attention should be paid to the compatibility (especially chemical compatibility) with the reinforcement, and it is considered to suppress the interfacial reaction as much as possible during the molding of the metal matrix composite. Since the metal matrix composite material needs to be formed at a high temperature, in the preparation process of the metal matrix composite material, the metal matrix and the reinforcement are easily chemically reacted between the fiber and the metal under the high temperature thermodynamic imbalance state in the high temperature composite process. The formation of a brittle reflective layer at the interface has a great influence on the strength of the composite. Furthermore, since the base metal often contains different types of alloying elements and the reaction of the reinforcement and the resulting reactants are different, it must be fully considered when selecting the matrix alloy composition.
Next, look at inorganic cementitious materials, which mainly include cement, gypsum, rhombohedral and water glass. Among them, fiber-reinforced cement-based reinforced plastics are the most studied and applied. Let us look at the characteristics of cement-based materials. The cement matrix is ​​a porous system with a pore size. Its existence not only affects the performance of the substrate itself, but also affects the interface bonding between the fiber and the substrate. The elastic modulus ratio of fiber to cement is not large, and the stress transfer effect in fiber reinforced cement composite is far less than that of fiber reinforced resin. The cement substrate has a low elongation at break, and the cement substrate is cracked before the fiber has been pulled out of the cement substrate. The cement substrate contains powder or granular materials and is in point contact with the fibers, so the amount of fibers is greatly limited. The cement substrate is alkaline and can protect metal fibers, but is detrimental to most mineral fibers.
The hydration process of the matrix is ​​quite complicated and the physical and chemical changes are diverse. Due to the limited space, it is omitted here.
Let's look at ceramic materials, ceramics that make metal and non-metallic solid compounds that are bonded to covalent or ionic bonds. Unlike metals, they do not contain large amounts of electrons. The disadvantages and advantages are equally obvious. After the birth of ceramic matrix composites, the advantages of ceramics were retained, and the disadvantages were compensated for by the addition of reinforcing materials, which made ceramic materials enter a new development field. Ceramics used as matrix materials should generally have high temperature resistance properties, good interfacial compatibility with fibers or whiskers, and good process properties. Commonly used ceramic substrates mainly include glass, glass ceramics, oxide ceramics and non-oxide ceramics.
Another important class of substrates is the polymer matrix. As the name implies, the main component of this matrix is ​​the polymer. There are various types, such as unsaturated polyester resin, epoxy resin, phenolic resin and various thermoplastic polymers. The roles and relationships of the various components are complex. There are generally three main functions: sticking the fibers together; distributing the load between the fibers; protecting the fibers from the environment. Since there is no such material involved in this department, a brief description is given, if necessary, for reference.
The fiber acts as a reinforcing component in the composite and is the main bearing component. mainly divided:
1. Glass fiber and its products: It has some excellent properties, high tensile strength, fireproof, mildew proof, high temperature resistance and good electrical insulation performance. Except for HF, concentrated alkali and concentrated phosphoric acid, all chemicals and organic solvents are used. Has good chemical stability. Disadvantages are brittleness, non-wear resistance, irritation to human skin, and the like.
2. Carbon fiber: the specific gravity is between 1.5 and 2.0, the thermal expansion coefficient is anisotropic, the thermal conductivity is directional, the specific resistance is related to the fiber type, and the high and low temperature resistance is good. In addition to being oxidized by a strong oxidant, the general acid and alkali is Inert, oil resistant, radiation resistant, toxic gases and decelerating neutrons.
3. Aramid fiber (organic fiber): high tensile strength, high modulus of elasticity, low density, high thermal stability, anisotropy of thermal expansion coefficient, good dielectric properties, but susceptible to various acid and alkali corrosion, water resistance Bad sex.
4. Other fibers: from silicon carbide fibers, boron fibers, whiskers, alumina fibers, and the like.
The combination of the above matrix and reinforcing materials enables people to manufacture special composite materials according to their own requirements and meet people's needs on a material basis.
Second, the interface of the composite material and the surface treatment of the reinforcing material The interface of the composite material refers to a small area in which the chemical composition between the substrate and the reinforcement changes significantly, and which constitutes a combination of each other and can be loaded and transferred. The functions of the interface can generally be summarized as: transfer effect, blocking effect, discontinuous effect, scattering and absorption effect, and induction effect. These effects on the interface are properties that are not found in any single material and play an important role in the composite. The effect of the interface is related to the interface state, morphology and physico-chemical properties, as well as the infiltration, compatibility and diffusivity of the components on both sides of the interface. 
Due to the small and uneven interface size, the chemical composition of the base structure is complex, the mechanical environment is complex, and it is difficult to make a comprehensive analysis of the composition and phase structure. So far, the understanding of the composite interface is still insufficient, let alone a general model to establish a complete theory. So for the interface, you can only list the various theories.
For the polymer-based composite interface, the interface formation is divided into two stages: 1. contact and infiltration of the matrix with the reinforcing fibers; 2. curing phase of the polymer. At present, some theories are: interface infiltration theory; chemical bond theory; physical adsorption theory; deformation layer theory; restraint layer theory; diffusion layer theory; weakening interface local stress action theory.
The interface to metal matrix composites is much more complex than polymer matrix composites. Table 2-1 lists several types of metal matrix composite interfaces. Among them, the type I interface is flat, the thickness is only the extent of the molecular layer, except for the original composition, the interface is basically free of other substances; the type II interface is a disintegrating dissolution-diffusion interface composed of the original constituents; The interface contains an interfacial reaction substance (interfacial reaction layer) of about sub-micron order. 
Abstract The first chapter summarizes the material basis of human survival and development. In the 1970s, people used materials and information as the pillars of social civilization; after the 1980s, the new technological revolution represented by high-tech groups, and new materials and information technology
Chapter 1 Overview Materials are the material basis for human survival and development. In the 1970s, materials and information were the pillars of social civilization; the new technological revolution represented by high-tech groups after the 1980s, and new materials and information technology and biotechnology were listed as important indicators of the new technological revolution. This is mainly because materials are an important part of the national economic construction, national defense construction and people's lives. As an independent new branch of science in materials science, composite materials have received extensive attention and are increasingly developed and widely used in many industrial sectors, becoming an important aspect of the development of new materials in today's high-tech development.