Title of Invention

METHOD AND METAL POWDER FOR THERMAL COATING OF SUBSTRATES

Abstract

P0'/SEO2/OO943 Page 3(4) yf9-06-2003 Ourref.:PC-2024149 W^^ CLAIM3 '1. Use of a rr.etal powder for thermal coating of / substrates, said powder essentially consisting of pre?-alloyed iron base powder particles having molybdenum particles diffu¬ sion alloyed to the base powder particles, / wherein the molybdenum particles originate froni/reduced m.olybdenum trioxide and wherein the amount of/molybdenum diffusion alloyed to the particles of the ba/e powder is above 2, preferably above 3, and most preferably/above ^ % by weight of the metal powder. / ' ' , 2. Use according to claim I, whereJm the amount of tr.olybdenum diffusion alloyed to the pa/ticles of the base powder is between 2 and 15, preferably between 3 and 10 %, and most preferably bef'Jeen 4 and 10 % t/y weight of the metal pow¬der . / 3. Metal powder for thermal ^oating of substrates, said powder essentially consisting of/pre-alloyed iron base powder , particles having molybdenum par/icles diffusion alloyed to the I base powder particles, wherein/the molybdenum particles originate from reduced molybdanuir. trioxide and wherein the amount of moiybden-ur. diffusioTi alloyed to the particles of the ■ base powder is above 4 % by ^eign't of the metal powder. 4. Powder according to/claim 3, wherein the amount of molybdenum diffusion alioye/d to the particles of the base powder is between 4 and 10/% by weight of the metal powder. 5. Powder according tio claim 3 or 4, wherein the pre-alloyed base powder is a ,gas-atomised powder. €. Powder according to claim 3 or 4, wherein the pre-alloyed base powder is a water-atomised powder. 7. Powder according to any one of the^^laims 3 - 6 , wherein the pre-alloyed base powder includes at least one of the elements selected from the group"consisting of carbon, silicon, manganese, chromium, molybdenum, vanadium and tungsten. XWAPATENT AB / ' Page 4(4) 1^06-2003 J Ourref.;PC-2p^l49

Full Text

o « ^■-■ O-.— ? ' 0 METAL POt^T)ER FOR THER,MAL COATING OF SUBSTRATES. FIELD OF THE INTv'EK'TIOK The present invention concerns thermal spi^ay pow¬ders, their production and use. Specifically- pne inven¬tion concerns the spray powders for therrr.al ^^oating of aluminiurr subs t rates . / / BACKGROUND OF THE INVEHTION Different methods for producing cc^tings on alumin¬ium substrates are previously known. Jhese methods are used in eg aluminium engine block having cylinder liners which are formed by thermal sprayii U.S. Pat. N'o. 2,588,422 discloses an aluminum engine block having cylinder liners whion are formed by thermal spraying. These 1 ir.ers are built* up m two layers on the untreated surface of the engine' block, the top layer being a hard slide layer such/as steel about 1 mm in thickness and the lower 1 ayey being a molybdenous interlayer about 50 microns /in thickness. The interlayer, containing at least 60% molybdenum, does not constitute a siide layer, but is necessary in order to bind the hard slide layer to Che aluminmm block. Preferably, the interlayer is rr.ade up of /pure molybdenum. The slide layer is a layer of hard metal/ as for example carbon steel, bronze or stainless steel, m which the steel may be an alloy containing nickeV, chromium, vanadium or molybdenum for example. In principle, this two-layer structure provides s good slide/layer, but the cost of the double coating is substantia In recent thermal spraying methods the thermal spray powders are made up/by a mixture of powdered steel with powdered modybdenura such as described in the US patent 6 095 107. The risk of segregation due to differences in properties betweem the base steel powder and the powder of crushed molybdenum is however a problem which may re- suit in non-uniform coatings. Another disadvantage/is that comparatively large amounts of molybdenum ar^ re¬quired due to the segregation effect. OBJECTS OF THE IN-VEKTIOM A rain object of the present invention is/to provide an inexpensive n-iStal powder for thermal coating of sub¬strates, especially for aluminium. Another object is to provide a powder ^hich does not segregate and wherein the amount of expensi/ve molybdenum alloying metal can be reduced in comparisgri with cur¬rently used methods. A further object is to provide a thermal powder, which has high deposition efficiency and gives excellent coating quality. / Anocher object is to provide a thermal powder giving coat ings at suitable porosity and oxide content and wherein Che pores are predominantly /closed, isolated and have an advantageous range of pore/iiameters. SLT-ir-!ARy OF THE IN'VENTION These objects are obtained Uy a metal powder com¬prising a pre-alloyed iron base/powder having particles of m,olybdenum, such as reduced rnolybdenum trioxide, dif¬fusion alloyed to the particles of the base powder. DETAILED DESCRIPTION OF THE INVENTION The type and particle size of the iron base powder is selected in view of the diesired properties of the fi¬nal coating and the substratfe. The base powders are pref¬erably pre-alloyed with elements desired in the coating. Also a minor part of the mo .ybdenum content may be in- cluded in the pre-alloyed powder. Other elements which may be included in the pre- alloyed base powder are C, Si, Mn, Cr, V and W. The pre-alloyed powder may be prepared by atomisation with water or gas. The particle sizes of the base powder are below 500 fim preferably between 25 and 210 ^m for PTA and less than 90 ^m, preferably lefes than 65 /xm for KVOF or plasma spraying. / ?.ccQrding to the present ir.vention the base powder and the alloying powder, i.e. the source of the alloying eleT,ent, which is preferably molybden'-im trioxide, are mixed according the prescribed formulation and the mix¬ture is heated to a temperature below the melting point of the obtained mixture. The temperature should be suffi¬ciently high Co ensure adequate diffusion of the alloying element into the iron base powder in order to form a par¬tially or diffusion alloyed powder. On the other hand the temperature should be lower than the temperature required for complete pre-alloying. Usually the temperature is be-tween 700° and lOOO'C, preferably be-tween 750° and 900°C, and the reduction is performed in a' reducing atmosphere, e.g. hydrogen, for a period of 30 Minutes to 2 hours for reduction of the molybdenum trioxi'ide, which is a pre¬ferred miolybdenum source. As an /klternative molybdenum source metal lie tr.olybdenum may ^e used. In this context it may be mentioned that metalV powders having molybdenum diffusion alloyed to the base/powder particles are previously kncwn from e.g. tne Japanese patent publications S-209 202, 63-137102 and 3-264 642. These known powders are, however/ used within the powder metallurgical industry for/producing sintered products of various shapes and sizes./Furthermore, and in contrast to the powders according to/the present invention, these known powders often have' not only molybdenum but also copper and/or nickel dijtfusion alloyed to the base powder particles. In these known powders the content of the diffusion alloyed molybdenum is usually low, whereas in the inventive powder cor thermal coating the diffusion alloyed molybdenum should be high in order to obtain an efficient sliding. So far the most interesting results have been obtained with powders having a content of diffusion alloyed molybdenum above about 4% by weight, it should also be observed that only molybdenum is diffusion alloyed to the base powder particles in the powder iised for thermal spraying according to the present invention. The upper limit of this diffusion alloyed molybdenum is decided by how much molybdenum the base parcicles can carry which seems to be about 15 % by weight^ see below. The particle size of the final thermal spray powder IS essentially the same as that of the prje-alloyed base powder as the molybdenum particles whict/are obtained when the molybdenum Crioxide is reduceca are very small in comparison with Che particles of the iDase powder. The amount of Che Mo which is diffusionyelloyed to the base powder should be aC least 2 % by waaght of Che total pow¬der composition. Preferably the amount of Mo should be between 2 and 15 and most preferably between 3 and 10 % by weight. The different methods for/applying the diffusion al¬loyed powders on the metal base substrate are spray or weld cladding process, such^es flame spray, HVOF and plasma spray or PTA. The invention is further illuscraced by, buC should not be limited to, the fii^lowing preparation and example. Example For the experiment on the new material for Chermal coating based on wat^r atomised Fe based [Fe-3Cr-0,SMo) +5% Mo. Used base materials and chemical analysis: Water atomised iron powder (Fe-3Cr-0,SMo)-71 ^m Molybdenum, trioxiqe M0O3 {Average parCicle size 3-7 (im) P0'/SEO2/OO943 Page 3(4) yf9-06-2003 Ourref.:PC-2024149 W^^ CLAIM3 '1. Use of a rr.etal powder for thermal coating of / substrates, said powder essentially consisting of pre?-alloyed iron base powder particles having molybdenum particles diffu¬ sion alloyed to the base powder particles, / wherein the molybdenum particles originate froni/reduced m.olybdenum trioxide and wherein the amount of/molybdenum diffusion alloyed to the particles of the ba/e powder is above 2, preferably above 3, and most preferably/above ^ % by weight of the metal powder. / ' ' , 2. Use according to claim I, whereJm the amount of tr.olybdenum diffusion alloyed to the pa/ticles of the base powder is between 2 and 15, preferably between 3 and 10 %, and most preferably bef'Jeen 4 and 10 % t/y weight of the metal pow¬der . / 3. Metal powder for thermal ^oating of substrates, said powder essentially consisting of/pre-alloyed iron base powder , particles having molybdenum par/icles diffusion alloyed to the I base powder particles, wherein/the molybdenum particles originate from reduced molybdanuir. trioxide and wherein the amount of moiybden-ur. diffusioTi alloyed to the particles of the ■ base powder is above 4 % by ^eign't of the metal powder. 4. Powder according to/claim 3, wherein the amount of molybdenum diffusion alioye/d to the particles of the base powder is between 4 and 10/% by weight of the metal powder. 5. Powder according tio claim 3 or 4, wherein the pre-alloyed base powder is a ,gas-atomised powder. €. Powder according to claim 3 or 4, wherein the pre-alloyed base powder is a water-atomised powder. 7. Powder according to any one of the^^laims 3 - 6 , wherein the pre-alloyed base powder includes at least one of the elements selected from the group"consisting of carbon, silicon, manganese, chromium, molybdenum, vanadium and tungsten. XWAPATENT AB / ' Page 4(4) 1^06-2003 J Ourref.;PC-2p^l49 \^ 8. Powder according to any one of the claims 3 y?, having a particle size below 500;jra, preferably between 25 and 210 pm. / 9. Powder according to any one of the claims/3 - 8, having a particle size below 90pm, preferably beVow 65pm. 10. Powder according to any one of the clairms 3-9 for thermal coating of aluminium substrates. / .f-'"^^^''^ U. Use of a metal powder for thermal coating of substrates, substantially as hereinabove described and illustrated with reference td the accompanying drawings.

Documents:

1804-chenp-2003 abstract duplicate.pdf

1804-chenp-2003 claims duplicate.pdf

1804-chenp-2003 claims.pdf

1804-chenp-2003 correspondence-others.pdf

1804-chenp-2003 correspondence-po.pdf

1804-chenp-2003 descrption (complete) duplicate.pdf

1804-chenp-2003 descrption (complete).pdf

1804-chenp-2003 drawings duplicate.pdf

1804-chenp-2003 drawings.pdf

1804-chenp-2003 form-1.pdf

1804-chenp-2003 form-18.pdf

1804-chenp-2003 form-26.pdf

1804-chenp-2003 form-3.pdf

1804-chenp-2003 form-5.pdf

1804-chenp-2003 pct search report.pdf

1804-chenp-2003 pct.pdf

1804-chenp-2003 petition.pdf