US1758473A - Coating articles, particularly with metals - Google Patents

Description

May 13, 1930. M. u. 'scHooP COATING ARTICLES PARTICULARLY WITH METALS Filed June 26, 1925 3 Sheets-Sheet l May 13, 1930. 4 M. u. SCHOOP 1,753,473

. comma ARTICLES PARTICULARLY WITH METALS Filed June 26, 1925 3 Sheets-Sheet 2 May 13, 1930. M. u. scHooP 1,758,473

COATING AR'IICLES PARTICULARLY WITH METALS Filed June 26, 1925 3-Sheets-Shee 3 'PatentedMay 1 3, 1930 V PATENT OFFICE m omen s'cnoor, or-f nonnee. swrrzannm ooa'rnm unease, rsa'rrcomtv wrrn imam Application died 1110", serial Io.

.;'.The present invention relates to improvements'm a method and a device for coatmg articles and particularly for producing, me-

tallic coatings.

6 With the present method the coating material is no longer used in the form of a wire as with the known metal spraying apgiaratus designed; as pistol, but in the form o metallic powder or metallic bronzes which are m 10 aconvenient manner melted to the surface of the article to be coated b means of a reducing melting flame. ereb exceedingly fine and strongly adhering yers are obtained which cannot be distinguished from 16 galvanic coatings and which show a homogenous metallic continuity. f

The so-called metallic bronze is the most suitable coating material. The present mvention has little in common with the known method of projectingthe molten articles of a wire towards the surface and t e apparatus for carrying into effect the present method has no longer an resemblance with the spraying istol; any urner used for antogenous wel g may be utilized.

The characterizing features of the new layers are thus essentiall different from those obtainedby the me od utilizing the pistol. constructional examples of the subiect matter of the present invention are 11 ustrated on the-accompanying drawmgs 1n Fig.1 shows-a welding burner of the inje'ctortype having a controlling screw for the acety ens and oxygen supply. 'f Fig .'=2'shows the burner according to Fig. 1 provided" with a nozzle head for producing the co atings.

hows the nozzle head. Fig. 4 is a detail of nozzle head, Fig. 3.

Fig. 5 shows an apparatus partly in section.

Fig. '6 is a longitudinal section of a nozzle head which maybe used on the apparatus Fig. 5. Fig. and

j Fig. 8 illustrates an apparatus in which 7 shows another form of apparatus,

too high in most cases.

"(such as grinding or polishing),

39,785, and: Switzerland! June 80, 1984.

the im elling vapor (pressure is produced from t e reducing me ium used.

' .In Fig. 3 the supply for the constituent arts of combustion gas for instance acetyene-oxygen is desi nated b 1; 2 is the channo 1 along which t e meta ic bronze is fed,

8 1s the supply conduit for the pressure medium, for instance compressed a1r, which has to accomfilish two tasks: 1(a) to increase the speed of ow of the metal 1c particles, (6 to reduce the temperature of the flame whic is The inner mouth piece 40f the nozzle (Fig. 4) is preferably rovided with helical grooves 5 in order to impart a swirling or rotatin ,motion to the mixture of air and metal at tl ie exit. Thereby an intimate contact with and distribution of the particles in the reducing zone of the flame is ensured. q

' 'The oxygen-acetylene flame has strongly reducing properties and this is advantageous as the products obtainable in the trade are mostly oxidized. When the flame cone as well as the feed of the metal are properly adjusted it is, possible for instance to produce nice compact coatin s of the normal typical salmon red of soun copperfrom dark coloured strongly oxidized copper power. The novel method of applying a coating by melting or welding is technically and economically superior to the known spraying rocess as may be seen with reference to igs. 1-4. The apparatus does notrequire any movable, delicate parts, no turbine for feeding the material, no ball bearings and does not have the characteristics of a sensitive precision instrument. The coatings are bright and, as has been mentioned above, of an extraordinary density and, smoothness; they do not require any further treatments which treatments are in most cases as expensive as the production of the coating. The cleaning by means of the sand blast apparatus is no longer required, the surfaces to be coated have only to be freed from grease. The metallic particles are in a molten state when they 'reach the surface to be coated, the latter is well heated by the oxygen-acetylene flame and the result is a so to speak welded-on, brilliant and dense metallic coating.

Numerous tests and observatlons have shown that the method is improved and mmplified-if the metallic bronze 1s introduced into the channel by means of the inflammable gas. Each single metallic particle is then forced to .pass the reducing zone o f the flame and to melt thereby. The poss1b1l1ty of msufliciently heated particles reboun from the surface to be coated is then tots y excluded, i. e. all of the metal of the powder 18 melted, a result of extraordinary technlcal, hygienic and economic importance.

In order to imparta greater speed of flow to the molten particles extruding together with the inflammable gas and to reduce at the same time the temperature of the flame cone which is too high in most cases, compressed air is fed at the mouth of the nozzle in a convenient manner for instance concentrically or through a slot, the quantity and the pressure of the compressed-air bein the greater, the lower the fusin point the coating metal is. This knac ensures that no metallic dust or vapour are generated, which molests the operators. The uantity of air supplied to and surrounding the flam'e controls its temperature, and the operator soon 'acquires the facility of adjusting this quantity-to the various conditions of the temperature. at the time of use.

These conditions are dependent upon the pressure of the gas or vapor propellin the metal powderg'the inflammability of this vapor, the melting oint of, the metal, the size of powder partic es, their condition of oxidation, and other'conditions.

If the quantityof air is too great this will be indicated by a rebound of'metal dust from the article being coated, if too small, either by too fluid metal deposit or by vaporization of the metal powder. With metals having a low fusing point, such as forjexample 'tin or lead, mixtures of "gases may be employed which give low temperatures (i. e. mixtures of illuminating gas and air-or of hydrogen and air).

Figs. 5 and 6 f the drawing serve to illustrate an apparatus-by means of which-a rudimentary experiment can be carried out showing the essence of the invention. The mixture of gas feel to an ordinary acetylene welding burner is led into a bottle 9..(Fi'g. 5), the contents of which, consistin for instance of copper powder, is whirl at m by the gas leaving the pipe 10 and is away through the pipe 11 to the burner 12; the two arrows at the: mouth of the burner indicate the compressed air which is -fed concentrically to the burner.

Fig. 6 shows in an axia-lsect'ion the mouth piece 12 of the burner, 12'} denoting the channel through which flows the gaseous mixture containing the metallic powder in suspencarried sion and 12 is the conduit for supplying compressed air. r The experiments may also be carried out by feeding pulverized coating material from a suitable container by gravity and in a controllable manner into the gas channel, the closed container being subjected to pressure for obtaining an equalization of pressure. An apparatus of this type is illustrated in a diagrammatic manner in Fig. 7 in which 9 de'notes the container having a conical bottom 13. A vertical iced screw 14 is provided which controls the discharge of the pulverized material-at the bottom of the container. 9. The combustible mixture flows through the condu'it lli which ends in a nozisle 16- and'cmates a suction action on the material discharged into the annular space 17 surrounding the'nozzle 16. The pipe leads the coating material suspended in the stream of combustible gas to the burner. The feed screw i i may be rotated by means of the'bevel gear- 19, 20 by a horizontal shaft 21 driven by *any means for instance by a pulley 22.

' Another manner of feeding the pulverized metallic particles is illustrated in 8. The material to be coated is mixed wit an easily evaporable liquid for instance benzol petrol. amy lace'tate and the like in a closed container 23 which is heated by a burner indicated at 24. A pipe 25 extends from above to near the "lower end of the receptacle 28 and the boiling mixture raises under the influenteoi the steam pressure and conveys thus vthe pulverized material over any length through the pipe 26. The latter ends in 'a nozzle 27 surrounded by the annular nozzle 2812 0 which the combustible gas or n is sup lied through the pipe 29.- Near the ice end o thepipe 26a further burnerhflmay be arranged which completely 'Ievaporates the liquid in which the. coating material is suspended so that a mixture of vapour vand .pulverized materialis discharged at the nolmle 27. This-device of feeding the pulverized coating material-ensuresa perfectly uniform supply. of the latter. Attention may he drawn to the fact that the velocity df the flowing combustible gas must 'exceed the fia'ime' velocity of the explosive mixture. Ohviously if 'ihstead-of the finished explosive mixture oxygenis-utilized for transportiugthe-metallic powder and the two gases are'caused-to mix only respectively.

lt-will 'berecognized how extremely simple and handy the whole inetallizator apparatus has become especially old metallizator, pistol working with wire. I I claim: iiprocessof producing coatings which eomprises mixing a metal powder with "H "uid combustible in a closed container, heating the "some ultimate result is obtained at 'the mixing cooker-the burner if compared with the the inixtureto'produce a vapor pressure on the su1 face of the-mixture to expel the mixture, heating the mixture after expulsion tovaporize the liquid content of the mixture and increase the velocity of the now vapor and metallic particlemixture, andburmng the resultant mixture in a jet.

In testimony whereof, I have signed my name to this sfifiiification. DR. X ULRICH SCHOOP.

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