China Extrusion Blow Molding Machines Factory

Because of the plasma with hightemperature, high enthalpy, high chemical reactivity, and have controllability tothe reaction atmosphere and the reaction temperature and other characteristics,display unique advantages in the synthesis of the powder material preparationand ball handling, cause bottle preform people’s attention.Currently, the plasma powder processingtechnology already has a considerable size production capacity. RF plasmatechnique has achieved the tungsten powder, molybdenum powder, rhenium powder,tantalum powder, nickel powder, copperpowder and other spheroidizing treatment of metal powder.
From the 1980s, China has began to explorethe use of plasma spheroidized tungsten powder, but there has been a slightoxidation phenomena on the spherical tungsten powder surface, in order toprepare pure spherical tungsten powder, it also need to conduct hydrogen reductionon the spheroidization processed powder, so that the production efficiency islow, cost more, difficult to achieve the requirements of industrial production.Recently, scientists have developed thefirst plasma powder processing system in China, the system uses a water-cooledquartz plasma torch greatly reduce the amount of inert cooling gas, successfullyavoid the oxidation of tungsten metal powder in spheroidization process. Use irregularshape tungsten powder as the raw material, the particle size in the range of5.5 ~ 26.5¼m, through plasma nodulizing handling to obtain a smooth surface,good sphericity powder, its spheroidization rate reached 100%, and remainssingle phase tungsten powder after spheroidizing. The bulk density of 26.5¼m particle sizetungsten powder after spheroidizing was improved from 6.80g/cm3 to 11.5g/cm3,the powder liquidity also improved markedly. The studies show that such aradio-frequency plasma processing method can prepared micron single phasespherical tungsten powder, does not exist powder oxidation problem, highproduction efficiency, low cost, suitable for industrialized productionrequirements. They also studied the influence of process parameters to tungstenpowder spheroidized, found the reasonable feed rate is an important factor toensure the powder spheroidization rate. Excessive feed rate can not satisfy theneed of tungsten powder absorb heat, melting and spheroidizing, also lead topart of the powder in the plasma running track deviate the plasmahigh-temperature region, make the powder absorbing not enough heat, resulting theprocessed powder reduce spheroidization rate. In addition, when the feedingrate is constant, the spheroidization rate reduced with the initial powder particlesize increased.
The smaller the initial powder particle size, the larger the specialsurface area, when the plasma absorb more energy in the crossing, it will moreconducive to powder spheroidization. Generally, as powder particle sizedecreased, the melting point reduced, absorb the same amount of energy is easierto spheroidizing. Therefore, under the same process parameters, smallerparticle size of the powder with higher spheroidization rate.Use RF plasma spheroidizing other metalssuch as non-ferrous metal powder. RF induction thermal plasma preparedsubmicron copper powder, when copper powder through plasma, appears gasification,nucleation, condensation. However, the low melting point metal in the plasmasphere process inevitably occur evaporation and gasification, the prepared metalpowder include a lot of fine spherical powder obtained by evaporation,coagulation, particle size range of the product distribution is broader. Thisis a problem to be solved.Source:

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