DE102008057686A1 - Gas mixture useful in thermal spraying, cutting and/or during surface treatment, consists of a mixture of argon, helium, nitrogen, carbon dioxide and/or hydrogen with hydrocarbon gaseous under normal condition - Google Patents

Abstract

The gas mixture comprises a mixture of argon, helium, nitrogen, carbon dioxide and/or hydrogen with hydrocarbon gaseous under normal condition. The mixture consists of doped quantity of nitrogen monoxide, nitrogen dioxide and/or oxygen. The hydrocarbon contains double- or triple bond and is acetylene. The mixture consists of 2-5 vol.% of hydrocarbon related to the total mixture. Independent claims are included for: (1) a method for industrial preparation of a gas mixture; and (2) a device for providing a gas mixture.

Description

Technical area

The Invention relates to a gas mixture, a pressure vessel, containing the gas mixture, and the use of the gas mixture, a method using the gas mixture, a device for Providing the gas mixture at the workplace and a method for the preparation of the gas mixture.

State of the art

conventional be during thermal spraying by means of arc, plasma and / or Laser mostly uses gas mixtures, which are mainly argon, Helium, nitrogen or hydrogen or mixtures thereof include.

acetylene (Ethin) has previously been used in conjunction with oxygen for gas fusion welding ("Autogenous welding") used.

Summary of the invention

In In a first aspect, the invention relates to a gas mixture comprising a mixture of argon, helium, nitrogen, carbon dioxide or hydrogen or their mixtures with a gaseous under normal conditions Hydrocarbon.

The gas mixture according to the invention may also contain doping amounts of NO and / or N ₂ O and or O ₂ .

In In a second aspect, the invention relates to a pressure vessel, which contains the gas mixture.

In In a third aspect, the invention relates to the use of the gas mixture during thermal spraying by means of an arc, plasma and / or laser.

In In a fourth aspect, the invention relates to a process for industrial Processing, in which with the help of a gas mixture, a thermal Spraying is made, characterized in that the gas mixture is a gas mixture according to the invention. optional Oxygen is added to the gas mixture on site.

In In a fifth aspect, the invention relates to a device for providing the above gas mixture, comprising Tank with liquid argon, nitrogen, carbon dioxide, hydrogen or Helium or mixtures thereof, a container containing the hydrocarbon optionally mixed with argon, nitrogen, carbon dioxide, Contains hydrogen or helium or mixtures thereof, and a device for mixing over lines with a Job for industrial processing using the inventive Gas mixture is connected.

In addition, one or more pressure vessels may be used, which contain argon, nitrogen, carbon dioxide, hydrogen or helium or mixtures thereof. In addition, one or more pressure vessels may be provided, which, optionally separated, NO, N ₂ O; and / or doping amounts of carbon dioxide, oxygen, NO and / or N ₂ O in admixture with helium, argon and / or nitrogen; and / or oxygen under normal pressure.

In a sixth aspect, the invention relates to processes for the preparation of the abovementioned gas mixture in which a gaseous hydrocarbon under normal conditions together with argon, nitrogen, carbon dioxide, hydrogen or helium or mixtures thereof and optionally doping amounts of oxygen, NO and / or N ₂ O in a pressure vessel is filled.

Description of the embodiments

It has surprisingly been found that the addition of a gaseous hydrocarbon under normal conditions to conventional gas mixtures of argon, helium, nitrogen and / or hydrogen and optionally admixture of carbon dioxide and / or doping amounts of NO and / or N ₂ O and / or oxygen to a considerable Increasing the efficiency of the thermal spraying by means of arc, plasma and / or laser leads.

Accordingly, a first aspect of the invention relates to a gas mixture of a mixture of argon, helium, nitrogen or hydrogen or mixtures thereof with a gaseous hydrocarbon under normal conditions, optionally further carbon dioxide and / or doping amounts of NO and / or N ₂ O and / or oxygen may contain.

Prefers the hydrocarbon has at least one double or triple bond on.

To the gaseous hydrocarbons include z. B methane, ethane, propane, cyclopropane, butane, iso-butane, cyclobutane and the hydrocarbons having a double or triple bond have, for. Ethylene (ethene), acetylene (ethyne), propene, propyne, 1- and 2-butene, isobutene, 1-butyne, 1,2-butadiene and 1,3-butadiene and their mixtures.

One particularly preferred hydrocarbon is acetylene.

Specific embodiments of the gas mixtures are:
Argon / acetylene, helium / acetylene, nitrogen / acetylene, hydrogen / acetylene and mixtures of two, three or all four of the non-hydrocarbon gases with acetylene, preferably argon / helium / acetylene.

The gaseous hydrocarbons generally make 0.001-30 Vol .-% of the gas mixture of the invention. Preferred amounts are 0.01-20% by volume, more preferably 1-10 Vol .-% and in particular 2-5 vol .-%. The in a special The quantities used depend on the type of process and on the processed materials.

Carbon dioxide, oxygen, nitric oxide and nitrous oxide (N ₂ O) may be admixed in doping levels of 10 vpm to 10,000 vpm (0.001 to 1.0 vol%), preferably 100 to 1000 vpm.

carbon dioxide may also be in amounts of usually 1 to 80 vol .-%, preferably 2 to 50 vol .-%, more preferably 5 to 20 vol .-% be mixed.

Further can also oxygen in amounts of usually 1 to 30 Vol .-%, preferably 2 to 20 vol .-% be mixed. In this case oxygen is added without pressure on site.

The gas mixtures according to the invention can be present in pressure vessels. Accordingly, a second aspect of the invention is a pressurized container containing the gas mixtures noted above except O ₂ .

a Another aspect of the invention is the use of the gas mixture during thermal spraying by means of an arc, plasma and / or laser.

there can the gases as premixed gas mixture (except Oxygen) from one or more pressure bottles or they can be mixed in a mixing device on site become.

The Task of the plasma during thermal spraying by means of an arc, Plasma and / or laser (a plasma also arises in the arc and usually also in the laser) is in a controlled way Transfer heat to the material. Because the theory of plasmas are exceedingly difficult, are the exact ones Processes in the plasmas generated by the said processes not well known and difficult to predict.

Without to be bound by theory, it is believed that in rare gas plasmas Heat is generated by the fact that on the one hand electrons and positively charged ions to atoms recombine and on the other hand the atoms release energy through shock.

In plasmas involving H ₂ -N ₂ molecules, it is believed that further energy can be released from the union of atoms to molecules.

It was surprisingly found that the invention used Hydrocarbons in particular increase the energy of the gas mixtures.

As large is the respective amount of energy that is used for heating of the material depends on the particular Conditions of the plasma and is difficult to predict.

The doping of gas mixtures with small amounts of CO ₂ , NO, N ₂ O and O _2, in particular during arc joining, is known (see, for example, US Pat. EP 0 544 187 B2 . EP 0 639 423 B1 and EP 0 640 431 B1 ). Among other things, a stabilization of the arc, a better energy coupling in the laser and generally a quality improvement is effected, which is observed even in the presence of small amounts of the inventively used gaseous hydrocarbons.

For example, CO ₂ , Nd-YAG, diode, disc or fiber lasers are used for laser processing.

The thermal spraying method in which the inventive Gas mixtures are used, divided into arc spraying, Plasma spraying and laser spraying.

At the Arc spraying becomes two wire-shaped, electrical conductive spray materials continuously under a given Angle fed to each other. Between the spray wires (Electrodes) burns with an arc after ignition a temperature and melts the spray material. A strong one Gas stream atomizes the melt and accelerates the Spray particles on the workpiece surface, where they form a coating. Due to the process only metallically conductive, wire-shaped spray materials are processed. Air can be used as a nebulizer gas but the use of nitrogen and argon is common.

in the Arcing applied layers are characterized by a very good adhesion. The spray particles clamp with the base material. The method is particularly suitable for applications that require thick coatings or large surfaces affect.

The applied layers can, for. B. for insulation, wear protection and Gleitla serve.

It has now surprisingly found that the injection speed can be further increased when the nebulizer gas gaseous hydrocarbons, in particular acetylene added or the order rate is increased, ie thicker layers can be separated. The quality of the coating is also improved.

The Plasma spraying is another thermal spraying process. at this method are in a plasma torch an anode and up separated into three cathodes through a narrow gap. By a DC voltage is generated an arc between the anode and cathode. The gas or gas mixture flowing through the plasma torch is passed through the arc, thereby dissociated and ionized. The dissociation and ionization generate a highly heated, electrical conducting plasma (gas of positive ions and electrons). In these Plasma jet is entered through a nozzle powder, the is melted by the high plasma temperature. The process gas flow (Plasma gas stream) entrains the powder particles and hurls on the workpiece to be coated. By the extreme high temperature (up to 30,000 ° C) can almost all Materials, including high-melting (eg ceramic), are processed.

at Plasma spray coatings may be z. B. very hard, wear-resistant, almost dense layers with very good chemical resistance act.

The Gas mixture in the plasma coating can simultaneously as a transport gas and serve as a protective gas. Gases used are usually argon, Nitrogen, hydrogen or helium and mixtures thereof.

It has now surprisingly found that by the Addition of gaseous hydrocarbons, in particular Acetylene to which or the gas mixture (s) increases the injection speed can be or the order rate is increased, so thicker Layers can be deposited. The quality the coating is also improved. By the addition of Hydrocarbons, in particular acetylene, can also be used in coatings the carbon content is positively influenced, which in turn Properties of the coating material with respect to mechanical and tribologically improved.

The Laser spraying is another thermal spraying process. At the Laser spraying is a powdered spray additive over a nozzle in the focused on the workpiece Laser beam introduced and with the help of a gas on the material surface spun. In the focal spot of the laser creates a plasma, through both the powder and a minimal part of the material surface are melted and the supplied spray additive metallurgical is connected to the material.

It has now surprisingly found that by the Addition of gaseous hydrocarbons, in particular Acetylene, to the gas mixture as in the above thermal spraying method the injection speed can be increased or the order rate is increased, so thicker layers can be deposited, and the quality of the coating also improved becomes.

The Invention also relates to a process for industrial processing, in which made by means of a gas mixture, a thermal spraying is characterized in that the gas mixture is a gas mixture according to the invention. If necessary, the Gas mixture metered a doping amount of oxygen on site.

Further The invention relates to a device for providing the above gas mixture comprising a tank with liquid Argon, nitrogen, carbon dioxide, hydrogen or helium or their Mixtures, a container containing the hydrocarbon optionally in mixture with argon, nitrogen, carbon dioxide, hydrogen or Helium or mixtures thereof, and a device for mixing, over lines with a place for industrial Processing with the aid of the gas mixture according to the invention connected is.

In addition, one or more pressure vessels may be used, which contain argon, nitrogen, carbon dioxide, hydrogen or helium or mixtures thereof. In addition, one or more pressure vessels may be provided, which, optionally separated, NO, N ₂ O; and / or doping amounts of carbon dioxide, oxygen, NO and / or N ₂ O in admixture with helium, argon and / or nitrogen; and / or oxygen under normal pressure.

The invention also relates to processes for the preparation of the abovementioned gas mixture, in which a gaseous hydrocarbon under standard conditions together with argon, nitrogen, carbon dioxide, hydrogen or helium or mixtures thereof and optionally doping amounts of oxygen, NO and / or N ₂ O filled into a pressure vessel becomes.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - EP 0544187 B2 [0030]
• - EP 0639423 B1 [0030]
• - EP 0640431 B1 [0030]

Claims (14)

A gas mixture comprising a mixture of argon, Helium, nitrogen, carbon dioxide or hydrogen or mixtures thereof with a gaseous hydrocarbon under normal conditions. Gas mixture according to claim 1, characterized in that it further contains doping amounts of NO and / or N ₂ O and / or oxygen. Gas mixture according to claim 1 or 2, characterized the hydrocarbon is at least one double or triple bond and more preferably acetylene. Gas mixture according to one of claims 1 to 3, characterized in that it contains the hydrocarbon in a proportion from 0.001-30% by volume, preferably 0.01-20% by volume, more particularly 1-10 vol.% and in particular 2-5 vol.%, based on the total mixture. Gas mixture according to one of claims 1 to 4, characterized in that it contains oxygen in larger contains as doping. Pressure vessel, the gas mixture after a of claims 1 to 4 contains. Use of the gas mixture according to one of the claims 1 to 5 during thermal spraying by means of arc, plasma and / or Laser. Process for industrial processing, in which with the help of a gas mixture made a thermal spraying is characterized in that the gas mixture, the gas mixture according to one of claims 1 to 5. Process for industrial processing according to claim 8, characterized in that oxygen to the gas mixture on site is added. Apparatus for providing the gas mixture according to one of claims 1 to 4, comprising a tank with liquid Argon, nitrogen, carbon dioxide, hydrogen or helium or their Mixtures, a container containing the hydrocarbon optionally in mixture with argon, nitrogen, carbon dioxide, hydrogen or Helium or mixtures thereof, and a device for mixing, over lines with a place for industrial Processing with the aid of the gas mixture according to the invention connected is. Device according to claim 10, characterized in that further that one or more pressure vessels are acting, the argon, nitrogen, carbon dioxide, hydrogen or helium or containing their mixtures. Apparatus for providing the gas mixture according to claim 9, characterized in that there are further provided one or more pressure vessels which, optionally separated, NO, N ₂ O; and / or doping amounts of carbon dioxide, oxygen, NO and / or N ₂ O in admixture with helium, argon and / or nitrogen; and / or oxygen under normal pressure. A process for the preparation of a gas mixture according to any one of claims 1 to 4, characterized in that under normal conditions gaseous hydrocarbon together with argon, nitrogen, carbon dioxide, hydrogen or helium or mixtures thereof and optionally doping amounts of NO and / or N ₂ O and / or Oxygen is filled into a pressure vessel. Method according to claim 13, characterized in that the hydrocarbon is acetylene.