CN101954324B - Plasma spray gun used for low-pressure plasma spraying - Google Patents
Plasma spray gun used for low-pressure plasma spraying Download PDFInfo
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- CN101954324B CN101954324B CN2010102884901A CN201010288490A CN101954324B CN 101954324 B CN101954324 B CN 101954324B CN 2010102884901 A CN2010102884901 A CN 2010102884901A CN 201010288490 A CN201010288490 A CN 201010288490A CN 101954324 B CN101954324 B CN 101954324B
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Abstract
The invention discloses a plasma spray gun used for low-pressure plasma spraying, and belongs to spray equipment used for preparing metal and metal oxide or metal carbide coatings. The spray gun comprises a gun body, a cathode, an anode and a spray nozzle, wherein a club-shaped cathode with a conical head is arranged in the gun body; an external water-cooling cylindrical anode and an internal compressed spray nozzle which is connected with the cathode closely are arranged in front of the cathode along the axial direction; and a spray powder material is fed into the inlet of the spray nozzle, is heated and accelerated in the spray nozzle, is heated in plasma in a low-pressure environment after being sprayed out from the spray nozzle, and flies to the surface of a spraying workpiece. The positive electrode of a direct current power supply is connected with the anode while the negative electrode is connected with the cathode. The device of the invention has high powder heating capacity and is suitable for performing plasma spray in low-pressure or ultra-low-pressure environment.
Description
Technical field
The present invention relates to the spraying equipment of a kind of spray metal, metal oxide or metal carbides, relate in particular to a kind of plasma gun.
Background technology
Plasma spraying is to utilize electric energy that mists such as argon, hydrogen or helium are changed into high-temperature plasma and in anode, form plasma jet; Utilize its High Temperature And Velocity plasma gas stream that metal or metal oxide, metal carbides are ejected into the surface of workpiece, form the process of coating.The temperature of plasma jet, the distribution character of speed and pressure affect the fusing degree of powder granule in the injected plasma, the porosity of coating and hardness consumingly.And spray gun external plasma temperature and VELOCITY DISTRIBUTION situation not only depend on the design feature of plasma generator, and be relevant with plasma torch exterior circumferential environmental pressure again.Under environment under low pressure pressure, plasma is after the spray gun ejection, and plasma expands rapidly, and along with the reduction of ambient pressure, plasma density reduces, and the plasma free path increases.Plasma is divided according to Knudsen number (Kn) the heat transfer type of powder granule usually, and this dimensionless number is defined as the mean-free-path length λ of gas particle and the ratio of the characteristic dimension L of powder granule, i.e. Kn=λ/L.Plasma density is higher under the atmospheric conditions, and mean-free-path length λ is little, so the Knudsen number is less; General Kn＜＜1; This moment, the heat transfer of plasma and particle can be thought continuous media, and plasma is high to the powder granule heating efficiency, and it is this that air plasma spraying belongs to.In low pressure or ultralow pressure condition, because plasma density reduces the also corresponding increase of mean-free-path length λ; Kn＞＞1; At this moment, plasma reduces the powder granule heating efficiency rapidly, adopt discrete Study on processing method plasma and intergranular interaction.
Plasma spraying can be employed in the outside powder feeding of spray tip, from the inboard powder feeding hole powder feeding of nozzle with from three kinds of forms of anode inlet powder feeding.Preceding two kinds of powder are transported in the plasma after the arc root, and the influence of article on plasma arc characteristic is very little; And the anode inlet automatic powder feeding system is before the arc root, and the arc characteristic of article on plasma body is influential.From the stability of spraying and the making simplicity of lance driving device, outer powder feeding is favourable.This mode of air plasma spraying choice of equipment in therefore most industry.But, under low pressure or the ultralow pressure condition, because the outside Kn of spray gun＞＞1; Adopt outer powder feeding plasma spraying mode, certainly will require plasma gun must have enough big power, for example; Sulzer Metco AG ultralow pressure plasma spraying adopts electric current 2500A; The high-power plasma gun of power 150kW, this not only causes waste of electric energy, also can quicken the corrosion of negative electrode and anode arc.Also there are some low-voltage plasma spray guns to adopt the inboard powder feeding of nozzle; For example United States Patent (USP) 5679167; 5853815 adopt inboard powder feeding spray gun, and the powder feeding meeting of this mode improves the deposition efficiency of powder, but because nozzle and anode are same one; And external nozzles does not partly have water-cooled but, and having limited nozzle can not be oversize.The powder injection phase is nearer from anode export.The spray gun power of at present domestic and international in a word low pressure or ultralow pressure used for plasma spraying is higher than plasma spraying power under the atmospheric conditions far away, and low-voltage plasma spraying is difficult to the material of spraying high-melting-point, lower thermal conductivity as zirconia.From the great advantage of this mode of anode inlet powder feeding is that powder heats, and the deposition efficiency of powder is high in the spraying, and the shortcoming powder is piled up in nozzle interior easily, causes the coating quality problem, and it is fewer that commercial plasma spraying adopts.The inventor had had once designed and produced the internal powder conveying plasma spraying equipment, and Chinese utility model patent ZL99243441.6 and ZL 02251688.3 can spray ZrO under the atmospheric conditions at input power 6-8kW
2-8Y
2O
3Powder body material, and deposition efficiency reaches more than 50%, but because the internal structure design can not adapt to low-voltage plasma spraying.
Summary of the invention
For solving the deficiency of existing internal powder conveying plasma spraying equipment technology; Find through studying us; Under environment under low pressure pressure, the pressure of the outside plasma jet of spray gun reduces behind jet expansion rapidly, and is higher than the spray gun outside at nozzle interior pressure; Belong to Kn＜1 in nozzle interior, show that plasma is high to the heating efficiency of powder.According to high this principle of nozzle interior pressure, design is sent powder into nozzle entrance, and is inner at high pressure nozzle, the melting rate of powder is controlled at about 60%, jet expansion further heating reach fusing fully and part evaporation.Can under the situation that does not increase plasma gun power and air inlet body flow, accomplish heating like this to powder granule.Promptly designed a kind of low-voltage plasma spraying and used plasma gun, through changing nozzle interior size, shape; The control plasma is at nozzle interior pressure; Control powder molten state reaches under suitable input power, realizes plasma spraying under low pressure or the ultralow pressure condition.
Technical solution of the present invention is achieved in that
A kind of low-voltage plasma spraying is used plasma gun; Comprise rifle body, negative electrode, anode and nozzle, the positive pole of dc source is connected on the anode, and the negative pole of dc source then connects on the negative electrode; Be provided with the bar-shaped negative electrode of conical head in the described rifle body; The negative electrode front is provided with cylindric anode along axis direction, and anode inlet is provided with the even distribution rings of gas, anode export is provided with internal compression shape nozzle, and the internal diameter of nozzle exports from entering the mouth to and becomes big gradually; Sprayed on material powder powder feeding mouth is inboard at jet expansion, and high temperature plasma jet is sprayed the powder heat fused by nozzle.
Technological core of the present invention is to be provided with at the anode front end nozzle of special internal compression shape, and nozzle is outside water-cooled, according to fluid mechanics principle; The plasma that makes compression is through narrow nozzle passage, and spraying powder is in the heating of high pressure plasma nozzle interior, fusing; The control powder is about 60% in the fusing degree of nozzle interior, and nozzle interior is the compression horn shape, and smallest cross-sectional place internal diameter is 4～8mm; Nozzle length is 20～100mm, nozzle exit internal diameter 8～20mm.The design of nozzle interior size and powder kind, particle is formed relevant.Technical solution comprises that also the diameter of described negative electrode is 6～12mm, and negative electrode is meticulous, and when plasma spraying electric current during greater than 500A, the negative electrode scaling loss is serious, and diameter is excessive, needs corresponding increase anode internal diameter, is unfavorable for improving the nozzle interior plasma pressure.
Technical solution of the present invention comprises that also sprayed on material powder powder feeding mouth through the gap less than 2mm, is sent spraying powder into nozzle entrance between anode export and nozzle entrance.Perhaps, sprayed on material powder powder feeding mouth is positioned on the circumference of upstream side of the injector 2-8mm, through the side opening of two or more internal diameters less than 1.5mm, spraying powder is sent into nozzle interior.Perhaps, sprayed on material powder powder feeding mouth is positioned on the circumference of anode export end 2-8mm, through the side opening of two or more internal diameters less than 1.5mm, spraying powder is sent into anode interior.Spray starting powder in a word and must pass through the heating of nozzle interior high pressure plasma, quicken, from the inner nozzle ejection of given shape.
The invention has the beneficial effects as follows: 1. flowing down (600A) at low plasma electric can be under spray gun external dynamic environmental pressure 50Pa, spraying ZrO2-8Y2O3, and this moment, the plasma gun input power was merely 30kW.2. under the low pressure condition, spraying ZrO2-8Y2O3 can type of preparation columnar crystal structure coating.3. because plasma current is low, anode and cathode life obtain prolonging.
Description of drawings
Below in conjunction with accompanying drawing and concrete embodiment the present invention is done further description.
Fig. 1 is apparatus of the present invention structural representation.
Among Fig. 1: 1, rifle body, 2, negative electrode, 3, anode, 4, nozzle, 5, the even distribution rings of gas.
The specific embodiment
Specify the present invention below in conjunction with embodiment.
A kind of low-voltage plasma spraying of present embodiment comprises rifle body 1, negative electrode 2, anode 3 and nozzle 4 with plasma gun; The positive pole of dc source is connected on the anode 3; The negative pole of dc source then connects on the negative electrode 2; Be provided with the bar-shaped negative electrode 2 of conical head in the described rifle body 1, the negative electrode front is provided with cylindric anode 3 along axis direction, and anode 3 inlet is provided with the even distribution rings of gas 5, anode 3 outlets are provided with internal compression shape nozzle 4; Sprayed on material powder powder feeding mouth is inner at jet expansion, and high temperature plasma jet is sprayed the powder heat fused by nozzle 4.
Utilize present embodiment to carry out ultralow pressure plasma spraying oxide ZrO
2-8Y
2O
3, choose the ZrO of granularity 10-35 micron
2-8Y
2O
3Powder is a spraying raw material, under table 1 condition, has prepared the section coating of columnar crystal structure, and coating layer thickness surpasses 0.8mm.
Table 1 ultralow pressure plasma spraying ZrO
2-8Y
2O
3Parameter
Utilize present embodiment to carry out low-voltage plasma spraying SUS316L stainless steel, the SUS316L spherical powder of choosing granularity 25-50 micron is a spraying raw material, under table 2 condition, has prepared the stainless steel coating of equiax crystal structure, and coating layer thickness surpasses 0.5mm.
Table 2 low-voltage plasma spraying SUS16L parameter
The present invention is not limited to the foregoing description, and protection scope of the present invention is all classified in any equivalent concepts or change in the technical scope that the present invention discloses as.
Claims (4)
1. a low-voltage plasma spraying is used plasma gun, comprises rifle body (1), nozzle (4), is provided with the bar-shaped negative electrode (2) of conical head in the rifle body (1); The negative electrode front is provided with cylindric anode (3) along axis direction; The positive pole of dc source is connected on the anode (3), and the negative pole of dc source then connects on the negative electrode (2), and anode (3) inlet is provided with the even distribution rings of gas (5), anode (3) outlet is provided with horn shape nozzle (4); The internal diameter of nozzle (4) exports from entering the mouth to and becomes big gradually; The powder sprayed on material gets into nozzle interior from nozzle entrance, and high temperature plasma jet by nozzle (4) ejection, is characterized in that the powder heat fused: nozzle (4) inlet and anode (3) outlet closed butt joint; Nozzle (4) inside is the horn shape that different circular sections constitute; Inlet smallest cross-sectional place internal diameter is 4～8mm, and nozzle (4) length is 20～100mm, nozzle (4) exit internal diameter 8～20mm.
2. a kind of low-voltage plasma spraying according to claim 1 is used plasma gun; It is characterized in that: sprayed on material powder powder feeding mouth is positioned between anode (3) outlet and nozzle (4) inlet; Through gap, spraying powder is sent into nozzle (4) inlet less than 2mm.
3. a kind of low-voltage plasma spraying according to claim 1 is used plasma gun; It is characterized in that: sprayed on material powder powder feeding mouth is positioned on the circumference of nozzle (4) arrival end 2-8mm; Through the side opening of an above internal diameter, spraying powder is sent into nozzle (4) inside less than 1.5mm.
4. a kind of low-voltage plasma spraying according to claim 1 is used plasma gun; It is characterized in that: sprayed on material powder powder feeding mouth is positioned on the circumference of anode (3) port of export 2-8mm; Through the side opening of an above internal diameter, spraying powder is sent into anode interior less than 1.5mm.
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| Application Number | Priority Date | Filing Date | Title |
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| CN2010102884901A CN101954324B (en) | 2010-09-19 | 2010-09-19 | Plasma spray gun used for low-pressure plasma spraying |
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| CN2010102884901A CN101954324B (en) | 2010-09-19 | 2010-09-19 | Plasma spray gun used for low-pressure plasma spraying |
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| CN101954324A CN101954324A (en) | 2011-01-26 |
| CN101954324B true CN101954324B (en) | 2012-05-30 |
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Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102524323B (en) * | 2012-01-14 | 2015-04-01 | 中山市恒鑫聚诚工业设备有限公司 | Automatic egg paste spraying device |
| CN103533738A (en) * | 2013-10-21 | 2014-01-22 | 芜湖鼎恒材料技术有限公司 | Nozzle of plasma spray gun |
| CN105018878B (en) * | 2014-04-17 | 2018-09-11 | 北京联合涂层技术有限公司 | Rotating plasma spraying equipment |
| CN104602429B (en) * | 2015-01-30 | 2017-01-25 | 清华大学 | Warm plasma generator |
| CN104869741B (en) * | 2015-06-22 | 2017-08-04 | 衢州昀睿工业设计有限公司 | A kind of plasma torch for being used to gasify |
| CN105228329A (en) * | 2015-10-30 | 2016-01-06 | 中国科学院力学研究所 | A kind of method and arc plasma generator disperseing the electric arc raising generator life-span |
| CN109536874B (en) * | 2019-01-22 | 2024-01-09 | 中国人民解放军陆军装甲兵学院 | Inner hole plasma spraying device with deflection angle spraying function |
| CN114717545A (en) * | 2022-03-24 | 2022-07-08 | 沈阳工业大学 | Plasma-assisted cold spraying device and processing method for high-melting-point metal material |
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|---|---|---|---|---|
| CN2411260Y (en) * | 1999-08-27 | 2000-12-20 | 高阳 | Low-power high-efficiency plasma spraying device |
| CN2712471Y (en) * | 2004-06-29 | 2005-07-27 | 宝山钢铁股份有限公司 | Plasma spray gun for spraying composite material |
| RU2320102C1 (en) * | 2006-05-30 | 2008-03-20 | Государственное образовательное учреждение высшего профессионального образования Восточно-Сибирский государственный технологический университет | Spraying plasmatron |
| CN101289744A (en) * | 2008-05-16 | 2008-10-22 | 中国人民解放军空军雷达学院 | Supersonic reaction plasma spray gun |
| CN201172684Y (en) * | 2007-05-23 | 2008-12-31 | 上海大豪纳米材料喷涂有限公司 | Plasma spraying gun |
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Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN2411260Y (en) * | 1999-08-27 | 2000-12-20 | 高阳 | Low-power high-efficiency plasma spraying device |
| CN2712471Y (en) * | 2004-06-29 | 2005-07-27 | 宝山钢铁股份有限公司 | Plasma spray gun for spraying composite material |
| RU2320102C1 (en) * | 2006-05-30 | 2008-03-20 | Государственное образовательное учреждение высшего профессионального образования Восточно-Сибирский государственный технологический университет | Spraying plasmatron |
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