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The resin carbon will also exhibit stress graphitization

There are two ways to improve the Different Size Graphite Electrode resistance of carbon / carbon: adding antioxidants to reduce the oxidation rate or blocking oxygen on the surface coating of the parts. At present, the only structural materials that can work normally at a high temperature of 1600 ° C to 2000 ° C are carbon / carbon composite materials, which have the following advantages when used in the hot end parts of aeroengines: (1) It can still maintain strength without reducing above 1600 ° C; )

Reduce the weight of the engine and increase the thrust-to-weight ratio; (3) Reduce additional cooling, increase the operating temperature and improve the thermal efficiency of the engine. Once the cross section of the fiber is exposed, the fiber is rapidly ablated from the core and silicon carbide is left Surface shell. The high-temperature anti-oxidation coating is the main research content of carbon / carbon composite anti-oxidation, and the current anti-oxidation research is also focused on this aspect. SiC or Si3N4 anti-oxidation coating system can only be used under the temperature below 1700 ℃,

carbon / carbon anti-oxidation coating above 1700 ℃, must choose new materials or open up new ways, such as the use of iridium, platinum group Alloys and their compounds. Because carbon atoms have a strong affinity for each other, the carbon / carbon composite material has good stability at low or high temperatures. In addition to thermosetting resins, some thermoplastic resins can also be used as precursors for matrix carbon, such as polyetheretherketone (PEEK), polyetherimide (PEI), etc. Li Hejun. (2) Light specific gravity (less than 2. CVI process flow The prefabricated reinforcement is placed in a special CVI furnace, heated to the required temperature, and the hydrocarbon gas is introduced.

However, under the action of high temperature and high pressure, the resin carbon will also exhibit stress graphitization.; there are also many oxidation barriers studied, such as SiC, Si3N4, B4C , MoSi2, and carbides or oxides of Zr, Hf, Nb, Ta, etc. Although the CVI process cycle is longer, the overall performance of the prepared carbon / carbon composite material is better than the liquid phase impregnation method, and by changing the CVI process parameters, carbon / carbon composite materials with different structures and different properties can also be obtained. In order to improve the bonding state between the components in the matrix, the co-deposition technology of the carbon matrix and the ceramic matrix can be used.

The appropriate addition of sulfur and its hydride

The overall structure is a concentric hollow structure with tree rings. The preparation of VGCF has unique advantages: namely, ① the preparation process is simple, without the necessary process steps of OPCF manufacturing such as spinning, pre-oxidation, carbonization, and carbon fiber can be directly catalyzed by low-carbon hydrocarbons through high-temperature pyrolysis. This method uses ferrocene and other organometallic compounds as precursors to generate metallic iron particles through pyrolysis, disperse and float in the reaction space, and act as a catalyst to catalyze the fission of the cracked carbon ’seeds’ to form VGCF. The reaction temperature is 800 ℃ ~ 1300 ℃,

the appropriate addition of sulfur and its hydride can improve the density of VGCF, and is an additive in the preparation of VGCF. Through the choice of catalyst (such as the use of Ni-based catalyst particles) or the adjustment of the metal catalyst fine particle size (controlled to nano-scale particle size) can form spiral (spring tube) carbon, or single-layer carbon tube (nano carbon tube) The series of products are all molecular grade materials with excellent performance and wide application. In view of this, the ’floating growth substrate’ floating catalyst method was developed.

The former is to disperse catalyst particles (Fe particles) on a substrate (graphite, ceramics, etc. VGCF is a crystalline structure in which carbon atoms are arranged with SP2 (graphite and fullerene) as the inner layer, and the outer layer is a pyrolytic carbon stack.

The conversion rate of carbon source into fiber is over 60%. The high conductivity, high thermal conductivity, nuclear graphite electrode FOR EAF shielding, high heat resistance, biocompatibility and other characteristics of VGCF make it suitable for various functional materials. The carbon source (benzene, etc. Professor Hengfu Oyama of Shinshu University in Japan first developed this CF

A flame barrier is added under the carbon rod

6. The temperature control graphite electrode company is equipped with manual and automatic PID adjustment, which can automatically track and set the best PID value. The entire power distribution is distributed through air switches, and the air switch capacity is selected according to the power of each part; each temperature zone is controlled by an independent air switch. 6.10. Mechanical part 7.3 Push plate size: 340 × 340 × 30 (L × W × H) mm. 6. 7. 4.

Records of the number of pushers pushed.I. A flame barrier is added under the carbon rod in the sintering area of ​​the kiln to prevent the volatile substances in graphite from corroding the ceramic tube and improve the carbon rod Service life, on the other hand, when the ceramic tube or carbon rod is broken, the broken carbon rod and ceramic tube will not fall into the kiln, which improves the reliability of the kiln operation. Electrical part: 6.1

The industrial control computer is used to comprehensively monitor the temperature, speed and alarm events of the electric furnace.7 Water-cooled jacket can withstand a certain pressure, so that the circulating water is operated under closed-loop pressure.9 Furnace surface temperature rise: ≤60 ° C (based on the surface thermometer). The main limit switches are Omron products. 4.5 kg (excluding push plate).1

The outer surface of the furnace is sprayed with silver powder paint, and the external board is sprayed with plastic. 8. There are manual operation button stands at both ends of the electric furnace, which is convenient for automatic manual adjustment.2 Precision speed regulating valve, throttle valve, solenoid valve and speed regulating valve in hydraulic system are selected from Taiwan Asada accessories. 100 process curve memories. The firing curve is displayed directly.4 Maximum temperature: 1200 ° C (based on the imported temperature measurement block).10. 3.

The first type of granular activated carbon used in the field

And fast and selective. The first process includes dehydration and carbonization, heating the raw materials, drying at a temperature of 170 to 600 ° C, and carbonizing about 80% of the original organic matter.0nm, mesopores 1-25nm, macropores gt; 25nm. The advantages are developed pore structure, large specific surface area, strong adsorption performance, low reservoir resistance, stable chemical properties, and easy regeneration.

Active carbon adsorption capacity (unit: ml / cm3): H2, O2, N2, Cl2, CO2 4. The first type of granular activated carbon used in the field of urban water treatment is made of wood, called charcoal. At present, the specific surface area test at home and abroad uses the multi-point BET method. The pore volume of the mesopores is generally about 0. ② The nature of the adsorbent depends on its solubility, surface free energy, polarity, the size and unsaturation of the adsorbent molecules, and the concentration of the attached substances. The High power Graphite Electrode data of the specific surface area of ​​activated carbon can only be obtained by using the BET method.5 ml / g, and average pore radius is 40 to 50A. Decomposes harmful gases such as formaldehyde, ammonia, benzene, cigarettes, oil fume and various odors in the air, especially carcinogenic aromatic substances. Its structure is formed by the accumulation of six-ring carbon.

Many adsorptions are reversible physical adsorption, that is, the adsorbed substance is a fluid, which is adsorbed by activated carbon at a certain temperature and pressure, and the adsorbed substance is desorbed again at a high temperature and low pressure, and the inner surface of the activated carbon is restored to its original state. The adsorption area per gram of activated carbon is equivalent to as much as eight tennis balls.

The pore size of coal-based activated carbon is somewhere in between. As activated carbon has a developed pore structure, a huge internal surface area, and good heat resistance, acid resistance, and alkali resistance, it can be used as a catalyst support. This capillary has a strong adsorption capacity, and because of the large surface area of ​​the carbon particles, it can fully contact the gas (impurities). (2) According to the custom: micropores lt;

The adsorption heat during liquid phase adsorption is small

When the pH value reaches a certain range, these compounds will dissociate, affecting the adsorption of these compounds. The pH value of the rhenium solution will also affect the solubility of the adsorbate (solute) and the charge of the colloidal substance (solute). As activated carbon can adsorb hydrogen and oxygen ions in water, it affects the adsorption of other ions. The effect of activated carbon adsorbing organic pollutants from water generally decreases with the increase of the pH value of the solution. When the pH value is higher than 9.0, it is difficult to adsorb, and the effect is better when the pH value is lower. In practical applications, the optimal pH range is determined through experiments.

Fourth, the impact of the solution temperature: Because the adsorption heat during liquid phase adsorption is small, the effect of the solution temperature is small. Tritium adsorption is an exothermic reaction. Adsorption heat, which is the total heat released by the adsorbent (solute) per unit weight of activated carbon, in KJ / mol. The greater the heat of adsorption, the greater the effect of temperature on adsorption. On the other hand, temperature has an effect on the solubility of the substance and therefore also on adsorption.

When water is treated with activated carbon, the effect of temperature on adsorption is not significant. 5. Influence of coexistence of multi-component adsorbents When using adsorption method to treat water, water is usually not a single pollutant, but a mixture of multi-component pollutants.

During adsorption, they can co-adsorb, promote each other or interfere with each other. In general, the adsorption capacity of multi-component adsorption is lower than that of single-component adsorption. 6. Adsorption operation conditions: Because of the adsorption of activated carbon in the liquid phase, the rate of external diffusion (liquid film diffusion) affects the adsorption, so the type of adsorption device, contact time (water flow rate), etc. have an impact on the adsorption effect. In summary, there are many factors that affect adsorption, and comprehensive analysis should be made. According to the specific situation, the best adsorption conditions are selected to achieve the best adsorption effect.

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