Small arch shed lettuce notes

The management of lettuce in the small arch shed is simple and the investment is small. The area of ​​one acre is less than one thousand yuan, and the lettuce can grow to 2-3 kilograms. The income of one mu of land can reach 10,000 yuan. There are a few things to note about:

First, we must grasp the time of planting. Lettuce is generally cultivated in the first autumn of the first year, and is planted in the winter. The stem of lettuce grows and expands with the growth of the plant, and the excessive moisture in the stem is prematurely planted, which is prone to freezing damage. Planting too late, the nutrients absorbed in the early stage cannot supply the needs of winter growth.

The second is to pay attention to the number and method of watering. Lettuce is planted from the first year to the next year, and it is usually enough to only pour water four times. The first water is poured after planting, and the second water is mainly frozen water. After the frozen water is poured, the scorpion is covered with the discarded grass hoe, which mainly serves as a heat preservation function to ensure that the lettuce smoothly passes through the winter. The last two waters are in the second year after the spring temperature rises and rises to the arch shed until about 10 days before harvest.

The third is to pay attention to topdressing. Each time watering, 60-70 kg of high-potassium compound fertilizer is used together, one is beneficial to the expansion of fruit, and the other is to prevent the excessive growth of the upper leaves caused by the partial use of high-nitrogen compound fertilizer, forming a canopy environment and increasing the incidence of diseases.

The fourth is to pay attention to disease prevention. Lettuce has few diseases. After the arch shed is set up, it should pay attention to the daily release of wind, reduce the humidity in the shed and reduce the occurrence of diseases. After the temperature rises, there is no need to cover the film. In daily management, chlorothalonil or ampicillin, mesomycin can be sprayed every 10-15 days to prevent diseases.

Graphite Block is a solid shape, which is usually made of artificial Graphite , graphite mould and so on. It also has small graphite blocks made of Flake Graphite , such as a carbon brush. Graphite is mostly powder, such as soil Graphite Powder , flake graphite and other powder.

Graphite blocks for silicon carbide furnace, graphite furnace and other metallurgical furnaces, resistance furnace for lining and conductive materials, and opaque graphite heat exchangers. Widely used in electronics, metallurgy, chemical industry, steel and other fields, the product quality is excellent, the performance is stable.

The function and use of high purity (isostatic pressure) graphite blocks

Production and processing of various materials, specifications of the graphite rods, graphite products, graphite block, graphite block, graphite plate, graphite tubes of rotary kiln, High Purity Graphite crucible, graphite ring, graphite boat graphite products, such as the opposite sex, with high temperature resistance, good thermal conductivity, melting high purity, strong corrosion resistance, long service life, etc. Create the graphite block of special rotary kiln in rotary kiln, including kiln head, kiln tail graphite block and Graphite Seal Block. With long service life, the attached impurity content is very few, with high volume density and strong anti-folding ability.

Graphite, graphite, soft, black grey; It has a greasy feel and can contaminate paper. The hardness is 1 ~ 2, and the hardness can be increased to 3 ~ 5 along the vertical direction with impurities. The proportion is 1. 9 ~ 2. 3. Scope of specific surface area is focused on the 1-20 m2 / g, under the condition of starvation, its melting point above 3000 ℃, is one of the most heat-resistant mineral. It conducts electricity and conducts heat.

There is no pure graphite in nature, which often contains impurities such as SiO2, Al2O3, FeO, CaO, P2O5 and CuO. These impurities often appear in the form of quartz, pyrite, carbonate and other minerals. In addition, there are water, asphalt, CO2, H2, CH4, N2 and other gas parts. Therefore, in addition to determination of fixed carbon content, the content of volatile and ash content must be measured.

The technological properties of Natural Graphite classification graphite are mainly determined by its crystalline form. The crystalline form of graphite minerals has different industrial values and USES.

1. Dense crystalline graphite:

Dense crystalline graphite is also called blocky graphite. Such graphite crystals are clearly visible to the naked eye. The particle diameter is greater than 0. 1mm, which is concentrated in 0.1-1m2/g than surface area, and the crystal is arranged in a disorganized and dense block structure. This kind of: the characteristic of graphite is high grade, the average carbon content is 60 ~ 65 %, sometimes reach 80 ~ 98%, but its malleable and slippery sex is not as good as flake graphite is good.

2. Special Graphite:

Graphene is widely used in industry and is used in almost every industry. Industrial use of synthetic graphite, or special graphite. According to its forming way can be divided into the following kinds.

1. Isostatic pressure graphite, the three high graphite that many people call, but not the third height is isostatic pressure.

2. Pressed graphite.

3. Extruded graphite, mostly electrode material.

(1) processing speed is faster: usually, graphite's machining speed can be 2~5 times faster than that of copper; The discharge process is 2~3 times faster than copper.

The materials are more difficult to deform: the advantages of the thin rib electrode are obvious. The softening point of copper is around 1000 degrees, which can be easily distorted by heat. The sublimation temperature of graphite is 3650 degrees. The thermal expansion coefficient is only 1/30 of copper.

(2) lighter weight: the density of graphite is only 1/5 of copper, and the large electrode can reduce the burden of machine tool (EDM). It is more suitable for use in large mould.

(3) smaller discharge consumption; Because the spark oil also contains C atoms, in edm, high temperature lead to spark came out of the oil C atoms are broken down, turned on the surface of Graphite Electrode form a protective film, compensate the loss of the graphite electrode.

(4) no burrs; After finishing, the copper electrode needs to be repaired by hand to remove the burrs. However, graphite processing has no burrs. It saves a lot of cost and is easier to realize automatic production.

(5) graphite is easier to grind and polish; Because graphite's cutting resistance is only 1/5 of copper, it is easier to grind and polish by hand.

(6) lower material cost and more stable price; Due to rising prices in recent years, and now isotropic graphite copper price is lower, under the same volume, the universality of toyotanso graphite products price is 30% ~ 60% lower than the price of copper, and the price is more stable, short-term price fluctuations is very small.

It is this incomparable advantage that graphite products gradually replace copper as the preferred material for EDM electrode.

 

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