CA1245107A - Method and apparatus for applying metal cladding on surfaces and products formed thereby - Google Patents

Abstract

METHOD AND APPARATUS FOR APPLYING METAL CLADDING ON
SURFACES AND PRODUCTS FORMED THEREBY

ABSTRACT OF THE DISCLOSURE

Small, preferably micronsized hollow glass or ceramic spheres or foaming agents for making such micronsized hollow spaces or voids are incorporated into a resin material which is formed into a layer and after curing of the resin layer, it is abraded, sand or grit blasted so as to rupture the outermost layer of spheres or voids to provide a plurality of undercuts or nooks and crannies. A thermally sprayed metal, such as copper, becomes embedded into the undercuts, nooks and crannies, such that the bond or adherent strength is greatly improved. This micronsized glass, ceramic spheres and/or pores greatly increases the bond strength by providing better undercuts in the surface to be sprayed by molten metal and provide the capability of depositing thicker layers without jeopardizing the bond.

Description

4S3~

~ETHOD AN~ APPA~ATU~ FOR APPLYING METAL CLADDING ON
SURFACES AND PRODUC~S FORMED THEREBY

8ACKGRO~ND AND BRIEF DESCRIPTION OF THE INVENTION

The appllc~tlon o met~l coatings to varloua surf~cee by meAns of ther~ally spreyed molten met~l p~rtlcle i~ well known ln th~ ~rt. The appllcatlon of ~ntl-foullng co~tlnga u~lng the thermal ~pr~ylng ts~hnl4ue to m~rlne fftructure~, partioularly hull~ of bo~ts ~nd ~hlps, 18 known, but th~ proces~ 1~ also appllc~ble generally to auch exemplary ~tructure3 a8 UnderWAter plllng~, power plant lnt~ke ducta, underw~t~r anergy conv~r~lon By~tem~ bouys~ drill plAtforms and the llke where the foullng by marlne growth inter~erQs wlth or lmpede~ the efflclent oper~tion of auch appar~tu~.
V~rlou~ ~y~teme h~ve been de~l~ed for applying antl-foullng ~ubstances, typlcally copper and copper ~lloy~, to ~rlne surfsce~, these lncluds copper foil~, p~nel~ or tlle~
whlch ~r~ adhered to hull ~urf~ces. The most modern of thesa ~re paint and coatlng technologle~ whlch depend on unlform con~umptlon of the blnder and toxln and bioclde and therefore ~re llmited by the thlckne~ or number of co~t~ngs ~pplied. In the tlle or foll m-thod~, paln~taklng t~lloring of lndlvldu~l panel~
or tlle~ to the complete hull surf~ce~ ha~, ln gener~l, not been ~t `~

~2gS~C~7 found acceptable by the marine trades. In Japanese Patent document 56-33485 of April 1981, copper and copper alloy are thermally sprayed on a prepared resin bond coating, which may incorporate talcum, mica or fiberglas~ to provide antifouling protection for hulls, etc.
One broad aspect of the present invention i5 to provide a matrix sy~tem for making a first surface for adherent reception of at lea~t the surface of a second material, including an adh~sive resin layer and at least a layer of ruptured spherical voids in the first surface.
Another a~pect of the invention resides in a metal clad surface which includes a layer of the remains of a plurality of ruptured hollow beads, forming a layer of undercuts, and an adhesive matrix ~ecuring the remains of a plurality of ruptured hollow beads to the ~urface with a solidified metal layer filling the layer of undercute to mechan~cally lock the metal layer to the surface.
More specifically, the present invention resides in a marine surface protected ~rom marine growth by an external layer of thermally sprayed molten metal selected from copper and copper based alloys. A matrix layer of undercuts, nooks and crannies is constituted by a layer of fractured, inorganic hollow ~pherical bodies with an adhesive layer securing the matrix layer to the marine surface. The layer of metal i~ ronstituted by a solidified layer of the molten metal filling and interlocking with the undercuts, nook~ and crannie~.
The present in~ention also re~ide~ in a system of applying a j" , . ~ " .~, 5~
- 2a -metal layer to a surface, including the step cf adhesively ~ecuring at least a layer of micron ~ized hollow glass or ceramic ~pheres to the surfa~e, rupturing a surface layer of the ~pheres and applying molten metal to the ruptured layer of the spheres.
A specific embodiment of the invention involves incorporat-ing hollow gla-~s or ceramic spheres in the micron~ize range (marketed under various trademarks such as MicroballoonsT~, Microspheres~M, or the depo~ition of a foamed re~ln surface onto the re~ln layer whlch can be an air, heat or UV cured resin.
This layer serves as the ~ealing layer and flrmly adhere~ the thermally sprayed anti-fouling coating. The mechanism i~
relatively slmple in that the heavily filled layer is abraded by sand~ng or grit blasting sufficient to rupture, sheer and/or fracture the embedded micronspheres, microballoon~ or foamed voids. A~ter the abrading process i8 complsted, the surface i8 vacuumed or washed clean to remove the abraded material so that the surface now repre~ents a porous surface with large number~ of undercut~, nooks and crannies. The sprayed ~olten copper flow~
into the undercuts, nooks and crannies and now becomes embedded into and mechanically locked to these pore~ and in this manner, the bond strength is mechanically fixed. The ant~-foulin~ syste~
includes a resin layer which could be a polyurethane, a polyester or epoxy re~in which serves three main function~: (1) provldes an adhesive between the marlne surface and a ~pray deposited copper or copper .~

~L24~ 7 costlng and ~) a seal layer to seal fine crack~ ln the gel coat of a flberglss~ hull, for example, and 3~ to prevent osmo~la ~nd a dieletrlc l~yer ln the c~ffe of a ~teel hull to prevent electrolytic corroslon effects.

BRIEF DESCRIPTION OF THE DRAWINGS:

Other ob~ect~. ~dvantages and featurea of the lnvention wlll becoma more apparent when con~idered ln llght o the ~ollowlng ~peclflcation and ~ccompanying drawlnga whereln:
Figure 1 la ~ close di~gram illuatrating the baalc ~tep~
of the met~l cladlng proce~ accordlng to tho inventlon, the b~lloons ~re enlargementa of croas-aectlona of the product ~8 lt emerge~ from each or the lndlcated ateps o~ the proceas, Flgure 2 1~ an enlsrged sectlonal vlew showing undercutA, nooka ~nd crannles and the filllng o ~ame wlth ~ copperJcopper alloy type metal for claddlng marine ~urface~ ~nd th~ llke, Flgure 3~ 18 a sectlon~l view of a mold for a fiberglaas hull of a boat and, Flgure 3b ia ~ aectional view of the hull r~moved from the mold ~nd b~ing therm~lly spr~yed ~lth molten copper.

DETAILED DESCRIPTIQN OF THE INVENTION

Applying met~lllc co~tings on surf~ces by thermnl apraying ia not, per ~a, new a~ ls a~own ln the ~bova noted ~Z451~7 3apanese patent publication ~nd ln ~iller patent 4,078,097. The thormal ~pray processes include meltlng powder in an electric or oxyacetylene ~rc and u~lng compre~sed ~ir or inert ga~ to propsl the molten particles toward the aubstrate at a high velocity.
Another form o thermal spray is the pla~ma arc whereby the powd~r or wlre lntroduced lnto a hlgh-veloclty plasma arc creatod by the rapid expanalon of gaa ~ubJected to electrlc arc heatlng ln a conflned volume. Another thermal pray process th~t 19 u~ed, 18 the combu~tlon of oxygen and fuel in a conflned volume and lta expanslon through A nozzle provlde the hlgh veloclty flow lnto whlch metal powder i~ lntroduced colncldental wlth the pro~ected g~ atream. Accordlng to this lnventlon, the nechanlsm of attachment 18 thMt molten partlclea of copper whlch can be travelling at hyper~onic speeds, greater than 5 times the ~peed of sound or eatlmated at 6,000 feet per second ~wlth certaln typea of equlpment) will flow lnto and mechanically lock with the undercuts, nooks and crannie~ and the first lRyer forms the b~sia upon whlch ~ub~equent layers of metal can be deposited to bulld-up to a desired thlckne~. The molten partlcles of metal forced into the nook~, crannlea and undercuts and roughne~s of the ~urface producea a much stronger and more dense flexible layer of cladded metal whlch, in the ca~e of copper or copper bs~ed alloya, sre very useful in providlng marine antl-foullng surface~.
harlne plping made of cOncretQ, steel, etc., whlch are expoaed to foullng, can easily have the internal ~urfacea thereof 5~t7 tre~ted ~ccordlng to the process of thls lnventlon to reduce ~nd ellminate flow lmpedlng ~rowth~.
As shown ln Flgur~ 1, the lnltial atep of ~pplylng cs~tlng o~ copper or copper alloy to a subatrate sur~ce such n~
~ ~nrin~ hull l~ ~urf~ce prepar~tion. After surface prep~rstlon, a ~ynt~ctlc ~oam resln co~tlng i~ epplied followed by abr~dlng or grit-bla~tlng the cured ~ynt~ctlc re~ln layer to for~ the m~trix of undercuts, nooks ~nd cr~nnie~ to recelve the thermsl ~pr~ying of copper And~or copper alloya. For the conventional gel CoAt of ~ flberglass hull, for ex~mple, the grlt blastlng 1 wlth No. 20-80 grit slllcon oxide, ~lllcon c~rbide, or alumlnum oxlde to re~ove the hlgh pollsh of the flniah ao that lt has ~
m~tt~ appear~nce whereln mlcroscoplc plt~, pores ~nd crev~ces ln t~e gel co~t are exposed ~nd depndlng upon the ch~r~ctar of the bl~st ~edi~, varlous ~orms of undercuts are made ln the aurf~ce.
It wlll be apprecl~ted that ~urf~ce prepar~tion wlll not ~lter the structur~l lntegrlty and hydrodynamic surHce of the hull.
Surface prepar~t~on conalsts of removlng mold release Mgent~ ~nd other forelgn matter ~rom the surf~ce of a new hull. The copper~copper alloy coating c~n be thermally spr~yed onto properly preparad metal, wooden or ferro-cement hull.
A ~yntacttc foam re~ln or g81 layer ll ls unlformly applled over the prep~red ~urf~ce by brush, trowel, spr~y or roller. As noted e~rller, the realn gel layer hAs lncorpor~ted thereln 20-200 percent by volume of micron~l~ed glQ~s or cer~mlc sphere~ 1~. In one preferred pr~ctice, the glAss sphere 111ed 5~L~7 resln la applled by commercl~l low pre~sure apray equipment 80 ~A
to not pr~maturely damage the sphere~. In one example of th~
~pray te~hnlque, aeveral l~yerA were ~pplled, ench to ~ flnal thickneas of about ten thou~andths of ~n inchv wlth tho glAs~
aphere ~llled resln layer havlng a thickneaa of about thlrty thousandths o an lnch. The mlcron~lze glaaa spherea Qppe~red to be unlformly dlAperaed ln the layer and when grit blasted or abraded ~nd apr~yed with molten copper, ~uperb mechanlc~l adheslon wa~ ~chleved. The resln i~ cured and then abraded or grlt-blasted sufficiently to ahear and fr~cture or rupture the mhedded sphere~ to provide numsrous undercut~, crevlcea, nooka and crannlea 13. Thla forma a matrlx o undercut~, nooks and cr~nnleA lnto which the molten metal flows on lmpact, and, upon Aolidlflcatlon, mech~nlcally lnterlock the metal l~yer~ to the surface to be protected. Thls poroua surface ls then vacuumed snd the molt~n metal 14 aprayed thereupon.
In a preerred embodiment, the mlcronAlzad sphQres, ln graded ~izes from about 10 to about 300 microns, comprlse between about 100 to 200 percent by volume of the realn, the resln being present in sufflcient amount to "wet' the surfaces of the spherea.
A urther method of apply~ng the matrix of mlcronslzed spheres whlch m~intalns ~urface fidellty and has a high productlon rate la to apply ~ cont of conductlve epoxy on the aurace. Whlle this 18 stlll wet and ~ticky, apply the mlcroballoons (hollow mlcrospheres) u~ing an ~lectrostatic ~Z~51~7 dl~charge ~un. Thls type of equipment placeA a charg~ on oach mlcron~lzed ~phere ~nd lt would be attracted to the Aurface of th~ conductlve epoxy layQr that ~orms part of th~ electrlc~l loop or ground.
The partlcle~ at fir~t become en~ulfed ~nd then would aaturate the surface uniformlly becAuse by lts very nature, when an ar~a is coated the partlcle~ wlll tend to be drawn to an are~
th~t 18 not co~ted. After a couple of p~aes, the surace should be satursted wlth ths flller ml~ron~lzed ~phere~. When the epoxy sets up or cures, the surface can be glven a llght grlt bla~t with a fine ~brasive. Thl~ will remove ths p~rtlcle~ that ~re only marginally attachsd and break the one~ on th~ ~urfsce that wlll provlde the m~trlx of undercuts, nooks and cr~nniea. After the llght grit bla~t, the aurface is power washed, dxied and then ~prhyed wlth the copper-nlckel alloy for antifoullng or any other metal. Thls wlll provlde a Amoother unlform coatlng wlth 1~B
efort and proces~ time.
It will be appreciated th~t aurface~ whlch are not desired to have a copper coating, such a~ above the w~ter llne, c~n be protected by m~aking t~pe, etc., ~ noted in our above-identlfied appllcation. The met~l co~ting layer 1 prefer~bly uniform but thl~ i~ not neceA~ary. In fact, in ~rea~
where there may be heavy mechanlcal wear or errosion, ~uch a~ on the keel, bow ~nd rudder areaA~ the metal layer can ea8ily be made ~lightly thlcker JU~t by ~praying addltional layera in tho~e are~.

~2~5~7 Several dlfferent type~ of hollow glas~ and ceramlc shere~ ha~e been utillzed. Thece were from the 3M Comp~ny, Emerson Cumming~ Corp., Pa Corporation, Micro-Mix Corporatlon, and Plerce ~nd Stevena Chemical Corpor~tion. Thoae ~arried in ~lze from 5 to 300 mlcrons. While it wa~ inltlally thought that the coaraer ~lzes would logically be preferrable, lt wa~ foun~
that the ~pr~yed copper deposit~ adheres very well on practlcally all slz0sr even blend~ of varlous hollow spheres glve excellent re~ult~ ln proportlons v~rylng from ~bout 20 percent to 200 percent by volume. It 18 deslreable that at lea~t a layer of the mlcron~lzed gla~a or ceramlc spherea be at the ~urface. In one e~mple, a layer of ~pheres floated to the surface with ~bout 20 percent by volume of 3M MlcroballoonsTM ~nd after grlt-blastlng the cured re~ln, the ~prayed copper flowed into the underco~ts, cavltlea and pores, nooks and crannles con~tltuted by the volds of the fr~ctured ~pheres to effect a ~trong bond. In the preferred practlce of this inventlon, the ~yntactlc reAin 1~
heavlly 111ed, tin one prefarred embodimentr 100 to 200 percent by volume o~ mlcron~lzed spheres relative to the amount o~ re~ln) and thua h~ thlxotroplc propertles auch that the spheres stay flxed, whlch la ~dvant~geous on vertical surf~cea.
Since the gl~ss or ceramic sphere3 are lntact, they can be premlxed ln wlth one or both component~ of a two component re~ln, or they can more preferably be ~dded and mlxed wlth the resin Qt the tlme o~ apppllcation to the ~ubstrate ~urfsce, or they can be ~pr~yed in the manner of the electrostatic spray ~29~S1~7 procea~ de~cribed above, and ~ mlxture of gla~ and ceramlc micron~ized ~phere~ can be used in pr~ctlclng th~ lnvention.
In a pre~erred practlce of the inv~ntlon, the copper~opper ~lloy met~l coatlng 1~ 1~ applied wlth 8 mlnlmum of at least two pa~e~ o~ the thermal ~pray Apparatu~. In the flrst pa~, the copper partlcles travelllng at hlgh apeed Aplatter and flow lnto the undercuts, nooka and crannles 13 and flll the sur~ace poroslty wlth molten metal to provide h firmly secured rough layer that hvoid~ detachment and d~lamlnation with the und~rcuta, nooks and crannles thereof provldlng atrong mech~nlcal adhe~lon and a firm ba~e to whlch sprayed molten ~etal applled on the second pa~B becomea flrmly aecured. In a preerred practlce of the inventlon, the metal 1~ applied to a thickne3s of about 3 to 12 mlls but lt wlll be appreciated that greater or les~er thickne~sea can be applled. For a commerclal ocean going v~a~el, 1~ to 15 mll thlcknes~ ahould last ~or about 15 ye~rs, whlch would provlde slgnlfic~nt reductlon in overall co~t of appllcatlon relative to lower inltlal coat paint based anti~oullng Ayatem~. After the flnal copper or copper alloy 19 applled, the extern~l ~urface can be smoothed by light wet ~andlng to remove ~mall proJection~, edge~ and produce a ~moother hydrody~nmlc aurf~ce. It will be appreciated that a single pas~
of the thermal apray apparatu~ can be u~ed ln many inst~nces, and, further the rate of movement of the spr~y apparatus relatlve to the Murfsce can be varled to vary the thlckne~s of applled metal. Moreover, the thermal ~pray apparatuA can be st~tionary ~Z~51~7 and the ~urface to be conted wlth metal moved relatlve thereto.
Accordlng to thl~ lnventlon, the resln, filled wlth hollow cer~mlc or gla3~ ~phareB i8 allowed to cure, ~nd ln 80me ~se~, the curlng 1~ enhanced by the u~e of ~ U.V. cur~ble re~in.
Commercl~lly pure copper ~nd copper-nlckel alloy~ ~re pre~er~bly u~ed ln the pr~ctice of the lnvention for antlfoullng purpo~e~. Dependlng on the thermal met~l ~prsylng ~pp~r~tus used~ commercl~lly pure coppar ~nd/or nickel-copper ~lloy~ (90-94 percent copper ~nd 10-6 percent nickel, wlth ~ 90 parcent copper, 10 percent nlckel ~lloy being preferred) ln the form of wlre~ or powdera are used in the pr~ctice of the inventlon. A~ noted abover ln the preferred practlce of the inventlon, the copper bAse m~tal and ~ntifouling layer is applled in at lea~t two passe~. ~ne would not go beyond the lnventlon ln u~lng two dlfferent types of therm~l spray ~pparatus durlng e~ch pa~s, lt belng apprecl~ted that lt 1B durlng the flrst th~t the molten partlclee of copper, tr~veling at high speed~, wtll att~ch ~nd embed themselves ln the undercuts, nooks ~nd ~r~nnle~ 13, se~l lay~r 11. During the second pass the molten p~rticles are forced lnto the undercut~ and roughne~ of the ~urf~ce left from the prevlou~ pass. PreferAbly the coatlng applled in the lnltl~l or flr~ pas~ 18 thinner thnn ln the ~econd and ~ucceedlng pa~seA.
Thl~ thln metQl coatlng provldss an excellent b~ for receivln~
~nd securely bonding the therm~lly ~pr~yed second pass.
In 80me C~IESC8, other conBtltuent~s~ BUCh aB dyee~! solld ~tate lubrlc~nt~ (to reduce ~rictlon) and other bioclde~ cnn be ~2~5~

blended into the copper ~nd/or copper-nlckel feed po~der~.
Copper 1~ softer than copper-nlckel alloy~ lf the use of the ~rea of the bo~t or 3hip i~ ~uch th~t hl~h ~br~lon reslstance 18 requlred~ the flnAl thermally sprayed metRl layer preferably wlll be copper-nickel ~lloy~
In the course of perfectlng thl~ lnventlon, v~rlou~
rQsln~ were trled and they all worked almo~t equally well from the ~dher~nce ~t~ndpolnt. The fln~l aelectlon la dlct~ted by the typ~ of ~urface to be treated. For inst~nce, polye~ter re~ln 13 preferred for fibergla~s hull~ since lt more clo~ely m~tche~ the polye~ter gelcoata Alre~dy present. However, more recent oxpert oplnlon lndictate~ the use of epoxy re~ln for better underw~ter ~ervice ~nd ~trength. The flnal thermally ~prayed ~et~l co~t can be lightly wet sanded aa 1~ the practlce with r~clng y~chts to produce a smoother ~urface.
In ~ ~urther em~odlment, a~ descrlbed l~ter hereln with regard to ~lgA. 3a and 3b. the aub~trate may be formed nub~equent to the vold contalnlng layer. For ex~mple, in a new ~iberglaas hulled boat constructlon, hollow ~pherlcal micronslzed be~d filled re~in i~ applied to the inslde of the mold prlor to, or ln place of, the gel coat in tho~e are~s whic:h ~re to have ~ntifoullng treatment ~ccording to thie lnventlon. Thareafter, the hull i~ formed by layering up the re~in impregnated fibergla~s m~ts rovlng, in the normsl m~nner. After removal ~rom the mold, the sphere fllled re~ln surf~ce ls abraded and~or grlt-blasted to form the undercuts, nooks and cr~nnie~ ~nd then S~ 7 sprayed wlth molten met~l part~clea.
A~ shown in Fig. 3(A), ~ bo~t hull mold 50 h~a A releae~
coating 51 on the lnner surfnce thereof ~nd ~ convention~l gel coat 52 to form the above the w~ter llne flnish (end of gel coat 58~ i~ applled to the releaae coat 51, m~king (not ahown ln Fig.
3(a)) being uned to asaure a str~ight llne for ~esthetic reasons.
Than, a layer of re~ln (an epoxy or polyester) layer 53 fllle~
with the ~phere~ 54 ls npplied to the remaining portlon~ of the mold 50 ~nd then the resin 1~ cured. Then, flberglasa ~nd resln 56 19 layered ln the mold in a conventlonal fa~hion to form the ba~lc hull structure of the ve~el. It wlll be appreclated that the lnterlor aurface of the cured re~ln l~yer 53 can be abraded or grlt bla~ted to form undercuts, pore~, nooks and crannlea beore the layering of the fiberqlass ~tructure~ to form ths hull. After curlng the resin ~nd fiberglasn matrix, the ~tructure 18 removed from mold 50~ the gel co~t 52 maaked by maskin~ material 59 and the external ~urface lff abraded or grlt hlaAted a8 indicated in Fl~. 3(b) and then the ~tep of thermal ~praylng of molten copper la carrled out on thlA prepared aurfnce in the manner deAcribed above.
Instead of met~l coatlng, the fr~ctured or crushed ~oid~
bound ln a resin matrix may be uaed aA an adherent surfhc2 for any other co~tlng or lamina.
Finally, lnsteQ~ of Aphere~ for produclng the vold~, ~lr bubblea can be formed in the realn, by a foamlng a~ent, for ~xample, after curing of the reain, the voida are fractured by ~Z~ 37 ~re~ing or grlt bla~ting to produ~e the desired undercut~, nooks ~nd cranniea whlch then provlde the mechanlcal locklng for the coating mnteri~l.
These are hollow cerAmic balloon~ Caold by Emer~on Cummlng6 Corpor~tion and P.Q. Corpor~tlon) ~nd ~re l~rger, stronger and cheaper than the glas~ typs snd provide 8 more rec~ptive ~urf~ce for the inltlal flr~t l~yer of thermally sprffyed copper coating. In this preferred e~bodiment7 the re~in wa~ an epoxy ~nd the l~rgast mlcroballoDn wa~ ~bout 100 ~icron.
The copper w~a ~bout .OOS" and spplied ln two pa~s~s of the thermally spr~yed copper.

ADVANTAGES OVER THE PRESENT STATE OF THE ART ARE AS FOLLOW5:

1. The co~tlng 1~ ~ contlnuous co~tlng of co~plete 100 percent ~ntlfoullng materl~l without the need of ~ blndes n~ ln regul~r p~lnt~ or co~ting~.

2. The co~ting, belng met~l (copper and copper-nickel ~lloys) i8 stronger than palnta and will not we~r or erode qulckly, especlally ~round bow ~nd rudder ~0ctlona.

3. Th~ co~ting ie very ductile from the very n~ture of the m~t~rlal, l.e., copper, and wlll not degrsde or beco~e brittle with ~ge ~ in the ca~e o degrad~tion of organlc blnder~

4. It la ~y to ~pply, ~lncs ~t 1~ ~prayed ~nd doe~ not requtre careful tailoring or curved sur~ce and powders Rnd S1~7 wlre~ ~re more economlc~l than the adheelve coated copper-nlckel ~oil~.

5. On copper-nlckel hulls of two Gulf Co~st ehrimp bo~t~, the aver~ge erosion w~ approxlm~tely 005 mll~yr. These qre f~st movlng commerclsl ~lshing creft. Slower moving aalllng ~nd plea~ure cr~t hulls ~re conserv~tlvely expected to erode at le~s th~n 1/2 mil~yr. Therefore, ~ coatlng of 6 tu 8 mil~ ehould conserv~tlvely l~t at leRat 12 yssrs. Pre~ent lnterv~ls for h~ullng, ~cr~ping, ~nd painting d~pend on w~ter temperture, u~u~lly ~ver~glng ~t leaat once e year.

6. Rep~lra can be e~ily m~de by llghtly grlt-bl~stlng the damaged are~, applying the ayntactic fo~m adhe~i~e ~nd ~brMdlng ~nd ~praylng ~n overl~plng co~t of copper/copp0r ~lloy.
To ~peed up ~uch rep~ir~, the reeln c~rrlea for the ~phereA can be ~ U.V. realn whlch cures more r~pldly under ultraviolet expo~ure.

7. The copper~copper-nickel ~lloy~ pr~sent conslder~bly le~ toxiclty ~nd handling problem~ ln comp~rl~on to the complex org~notln compound~.

8. Hydrodyn~mlc propertle~ of hull ~urf~ce~ are not ch~nged.

9. Since the copper/copper-nickel co~tlng~ are relatlvely thin~ flexibla, ~nd ~trongly ~dherent to the outer hull ~urf~ces by the mech~nic~l interlocklng of the metal when lt eolidlfle~ ln the undercut~, nook~ ~nd cr~nnle~ 13, they flex wlth flexture of the hull ~nd ~trongly re~l~t del~mln~tlon force~

51~7 thereby a~aurlng a longer llfe.

10. The unfractured or intact spheres provlde an lnaulatlng functlon.
ll. The coating h~ high "scrub~blllty" a8 compared to palnt~ slnce it la metal and not an org~nlc mAteri~l.
Samples wlth thermal spray coatlngs accordlng to thl~
lnventlon were tested in the Che~apeake Bay water~ durlng the ~u~mer of 1983. The rssults ~howed no blom~rine growth on the copper ~prayed Aurfacea~ whlle there wa~ con~lder~le growth and b~rnacle~ ~nd other marlne organism~ on the unco~ted portion of the te~t ~pecimen~.
Sample~ t~ted by Ocean Clty Reeesrch Corportlon in Ocean Clty, MarylMnd durlng the summer of 1983 and 1984, ~l~o showed no marlne growth ~nd the co~ting~ st~yed int~ct.
The denalty o the spray deposlts ~re not as den~e as a wrought materlal ~uch ~A a foll or pl~te, ~o there 1~ a lnrger mlcro~coplc surf~ce area pre~ent in the form of ~upurou~ oxlde per glven are~ and hsnc~ will expose ~ more hostile ~urface to mArlne orga~ism~.
The bA~lc lmprovemen$ ln thl~ inventlon 1~ the lncrea~ed fftrength of the bond between the m~tal coatlng &nd the subatrate ~urf~ce ~nd thl~ comee ~bout through ths formqtion of the matrlx of undercuts, nook~ ~nd cranniee for recoiving the llquld co~ting, preferably molten met~l particlee, the undercuta, nook~
~nd crannle~ belng formed by fr~cturinq or rupturing the mlronsl~ed gla~a or ceramlc sphere~ ln the outer ~urf~ce of the ~2~51~7 cured resin carrier.

While the invention has been described with reference to ~he antifouling treatment of copper and copper alloys or marlne surfaces, the invention in its most ba~ic aspect i5 applicable to cladding materials in general, and particularly metals, and more particularly copper, on any substrate surface.
While there has been shown and described the preferred practice of the invention, it will be understood that thi~
, disclosure is for the purposes of illustration and various omissions and changes may be made ~hereto without departing from the spirit and scope of the invention as set forth in the clalm~
appended here~o.

2" ~

Claims (53)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. In a marine surface protected from marine growth by an external layer of a thermally sprayed metal selected from copper and copper based alloys, the improvement wherein a layer of an adhesive resin is between said surface and said external layer of metal, a plurality of fractured inorganic hollow spheres in the interface between said resin and said external metal layer forming undercuts, nooks and crannies, said external layer of metal being constituted by a layer of solidified thermally sprayed metal particles sprayed in a molten state and filling and interlocking with said undercuts, nooks and crannies.

2. The invention defined in claim 1 wherein said adhesive resin layer is a syntactic foam coating having an abraded surface to form said fractured inorganic hollow spheres, and said thermally sprayed metal particles are embedded in said fractured inorganic hollow spheres of said syntactic foam coating.

3. The invention defined in claim 1 including a first metal layer with metal particles selected from copper and copper-nickle alloys embedded in said adhesive layer and said layer of thermal-ly sprayed metal particles is sprayed in a molten state at a high velocity on said first metal layer.

4. The invention defined in claim 3 wherein said first metal layer is copper metal and said thermally sprayed metal layer is copper-nickle alloy wherein the copper constitute 90-94 percent and the remainder is nickle.

5. The invention defined in claim 3 wherein said first metal layer is copper-nickle alloy and said thermally sprayed metal layer is copper.

6. The invention defined in claim 1 wherein said marine surface is a hull and said thermally applied metal layer is thicker in areas of possible mechanical abrasion and erosion, including the keel, bow and rudder areas.

7. The invention defined in claim 3 wherein said first metal layer and said thermally sprayed layer have a combined thickness of at least 3 mils.

8. The invention defined in claim 7 wherein said first metal layer is thinner than said thermally sprayed metal layer.

9. In a method of applying an antifouling coating to a marine surface of a metal selected from the group comprising copper and/or copper alloys - such as copper-nickel, the improve-ment comprising the steps 1) of grit-blasting said marine surface, 2) coating said blasted surface with a curable adhesive syntactic foam layer, 3) curing said curable layer, 4) grit-blasting said cured syntactic foam layer to produce undercuts, nooks and crannies in the surface thereof, and 5) thermally spraying the undercuts, nooks and crannies in said syntactic foam layer with molten particles of said metal in one or more passes thereof.

10. The method of applying an antifouling coating as defined in claim 9 wherein the step of 5) thermally spraying is selected from plasma arc or thermal spraying using electric arc or oxyacetylene with compressed air or gas and feeding powder or wire into the arc to deposit said molten particles on the said grit blasted surface.

11. The invention defined in claim 10 wherein step 2) coating said blasted surface with a curable adhesive syntactic foam layer is carried out by spraying a resin filled with 20 to 70 percent by volume of small sized hollow spheres.

12. The invention defined in claim 11 wherein said spraying of resin filled with small sized spheres is carried out at low pressure.

13. The invention defined in claim 11 wherein said curable layer is applied by spraying a plurality of layers of said resin filled with said small sized spheres.

14. A method of applying a metal layer to a surface comprising:
1) adhesively securing at least a layer of micronsized hollow glass or ceramic spheres to said surface, 2) rupturing a surface layer of said spheres, and 3) applying molten metal to the ruptured layer of said spheres.

15. The invention defined in claim 14 wherein said adhesive is a syntactic foam.

16. The invention defined in claim 14 wherein in step 1) the adhesive is a syntactic U.V. sensitive resin foam and including subjecting same to U.V. to cure.

17. The invention defined in claim 14 wherein said hollow spheres are mixed with the adhesive in a preparation of 5 to 30 percent by weight.

18. The invention defined in claim 17 wherein said hollow spheres are in a proportion of 50-200 percent by volume,

19. The invention defined in claim 14 wherein in step 1), the glass or ceramic hollow spheres are in a size range of 10 to 300 microns and are in a resin carrier in an amount up about 80 percent by volume.

20. The invention defined in claim 19 wherein said hollow spheres are of different sizes.

21. The invention defined in claim 14 wherein in step 1), the hollow glass or ceramic spheres are in a size range greater than about 10 microns and are in a resin carrier in an amount up to about 80 percent by volume.

22. The invention defined in claim 21 wherein in step 1), the hollow glass or ceramic spheres are in a selected size range in an amount between about 20 percent to about 200 percent by volume of a resin carrier.

23. A method for rigidly securing a protecting layer to a substrate surface comprising, 1) securing at least a layer of voids in a select size range in a hard resin matrix to said substrate surface, said voids being closed on all sides, 2) fracturing at least the voids in said matrix by abrading away at least a portion of the surfaces bounding said voids to form exposed undercuts, nooks and crannies in said matrix, 3) flowing said metal protecting layer into said exposed undercuts nooks and crannies.

24. The invention defined in claim 23 wherein said layer of voids in step 1), is formed by incorporating a foaming agent in a resin base.

25. The invention defined in claim 15 wherein said syntac-tic foam layer includes a foaming agent and said undercuts, nooks and crannies are formed by said grit blast rupturing at least the surface ones of the air spaces formed by said foaming agent.

26. A matrix system for making a first surface for adherent reception of at least the surface of a second material comprising a adhesive resin layer and at least a layer of ruptured spherical voids in said first surface.

27. The matrix system defined in claim 26 wherein said matrix is molded and consists of resin and a plurality of ruptured small sized hollow bead means, said hollow bead means being selected from the group comprising glass or ceramic spheres.

28. The matrix system defined in claim 27 wherein said small sized hollow beads range in size from about 10 to about 300 microns.

29. The matrix system defined in claim 28 wherein said hollow beads comprise 20 to 200 percent by volume of said matrix system when applied.

30. The matrix system defined in claim 29 wherein said matrix system is formed by spraying said adhesive resin with said beads therein upon a surface, curing the resin, and then rupturing at least the outer surface layer of said glass beads to form undercuts, nooks and crannies.

31. The matrix system defined in claim 26 wherein said matrix comprises a resin and a plurality of ruptured micronsized spheres selected from the group consisting of glass or ceramic spheres.

32. A method of improving the mechanical adherance between two materials, comprising:
1) embedding a plurality of small sized frangible hollow beads in one of said materials, 2) rupturing the surface ones of said frangible beads to form undercuts, nooks and crannies, and 3) flowing the other of said materials into said undercuts, nooks and crannies.

33. The method defined in claim 32 wherin the first one of said materials is sprayed upon a forming surface, said frangible hollow beads are glass and are ruptured by abrading, and said other of said materials is a molten metal that is sprayed upon said one of said materials and said undercuts, nooks and crannies.

34. A method of metal cladding a surface comprising, 1) adhesively attacking a layer of hollow glass or ceramic spheres ranging in size to about 300 microns to said surface, 2) rupturing at least some of said spheres to produce a matrix of undercuts uniformly over said surface, and 3) applying a molten metal upon said spheres to fill said undercuts, nooks and crannies with molten metal which flows into and conforms to the surfaces of said undercuts.

35. The method of metal cladding defined in claim 34 wherein step 1) includes incorporating said hollow ceramic spheres as the fill in an U.V. curable epoxy resin as a mixture spraying said mixture upon said surface and then curing said epoxy using U.V.

36. The metal clad surface comprising in combination, a layer of the remains of a plurality of ruptured hollow beads, said hollow beads being selected from the group consisting of glass and/or ceramic beads and ranging in size to about 300 microns forming a layer of undercuts, an adhesive matrix securing said remains of a plurality of ruptured hollow beads to said surface, and a solidified metal layer filling said layer of undercuts, to mechanically lock said metal layer to said surface.

37. The metal clad surface defined in claim 36 wherein said adhesive matrix is a U.V. cured epoxy.

38. The metal clad surface defined in claim 36 wherein said metal layer is copper metal including alloys thereof.

39. The metal clad surface defined in claim 38 wherein said surface is a marine surface and said copper metal inhibits incrustation of said surface.

40. In a marine surface protected from marine growth by an external layer of a thermally sprayed molten metal selected from copper and copper based alloys, the improvement comprising, matrix layer of undercuts, nooks and crannies constituted by a layer of fractured, inorganic hollow spherical bodies, an adhesive layer securing said matrix layer to said marine surface and said layer of metal is constituted by a solidified layer of said molten metal filling and interlocking with said undercuts, nooks and crannies.

41. The invention defined in claim 40 wherein said fractured hollow bodies are the remains of hollow micronsized glass spheres.

42. The invention defined in claim 40 wherein said fractured hollow bodies are the remains of micronsized ceramic spheres.

43. The invention defined in claim 40 wherein said adhesive layer is an epoxy resin.

44. The invention defined in claim 43 wherein said hollow bodies are selected from the group consisting of micronsized glass or ceramic hollow spheres.

45. The invention defined in claim 44 wherein said spheres range in size from about 10 to about 300 microns.

46. The invention defined in claim 45 wherein said spheres comprise from at least about 20 percent by volume of said epoxy resin.

47. The invention defined in claim 46 wherein said hollow spheres are in a proportion greater than 50 percent by volume relative to said adhesive.

48. The invention defined in claim 45 wherein said hollow spheres are in different sizes.

49. The invention defined in claim 44 wherein said micronsized spheres range in size from 10 to about 300 microns and comprise at least 20 percent by volume of said resin.

50. The metal clad surface defined in claim 36 wherein said metal layer is greater than 3 mils thick.

51. The invention defined in claim 40 wherein said marine surface is n portion of the hull of a vessel.

52. The invention defined in claim 44 wherein said micronsized spheres range from about 100 percent to about 200 percent by volume of said resin.

53. The invention defined in claim 44 wherein said micronsized spheres consist of a mix of glass and ceramic spheres.