CA1167224A

CA1167224A - Heat-recoverable devices

Info

Publication number: CA1167224A
Application number: CA000343114A
Authority: CA
Inventors: Edward S. Binkley
Original assignee: Raychem Corp
Current assignee: Raychem Corp
Priority date: 1979-01-05
Filing date: 1980-01-04
Publication date: 1984-05-15
Also published as: FR2445753A1; IT1196403B; JPS6346959B2; DE3000204A1; JPS5598481A; FR2445753B1; NL8000055A; GB2039654A; GB2039654B; BE880992A; IT8019045A0

Abstract

A B S T R A C T

The present invention concerns a novel device such as a pipe coupling connectable to at least one substrate and which comprises at least one heat-recoverable member adapted on recovery to cause at least one surface of the devise to be sealingly engaged with the substrate, the surface being coated with a sealant having dispersed a particulate filler which is adapted to bite into the substrate on recovery of the memory metal member.

Description

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The present invention relates to devices which are con-nectable to at least one substrate through the intermediary of a heat-recoverable memory metal member.
As is known, "memory metals", sometimes also called 'Imemory alloys" are metallic materials from which a heat-recoverable article can be made, that is an article which can be deformed from an original heat-stable configuration to a different heat-unstable configuration in which it will remain un-til raised above a temp-erature (or through a narrow temperature range) known as the transition temperature, when it will return or attempt to return towards its original configuration. It will be understood that the heat-recoverable article is capable of returning towards its original configuration without the further application of outside force.
Further information relating to such metals and their applications may be obtained by reference to United States Patents ~ Nos. 3,174,851; 3,351,463; 3,753,700; 3,759,552; 3,783,037;
: 4,019,925; 4,036,669i 4,067,752; 4,Q95,999 and United Kingdom Patents Nos. 1,327,441; 1,327,442; 1,395,601; 1,488,393; 1,420,682;
~;20 1,504,707; 1,553,427; 1,548,965; 1,554,431; 1,554,432; and 1,554,~23.

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De~Tices which are connectable to a~ least one subs~rate through the intermediary of a heat-recoverable memory metal mem}:er are known, e. g. as pipe couplings or as co~ec~ors for electrical conductors~r Such devices, whilst satisfactory in som~ situations, ar~ less so i~ others, for example, in coupli~y thln walled pipes of relatively soft metal such as alumi.~ or copper especially where the pipes: axe suhjec~ed ~o relatively high f~uid pressures, or i~ connecting certain eléctr~cal conductors especially where ~he conduc~ors ax~
coated wlth a~ oxid~ il~L as i~ a~uminium conauctors.

Accordingl~, the preser~ ren~io~ provides a aevice c:onT~ectable ta:. at: leas~ one substrat~ whic~ com~rises at least on~ heat--rec:o~rerahle m~mory ma~a:l member adapte~. os~ recovery to cause ~ l~ast: orl~ slLrfac:e o~ tha deYlce to be seallngly ç~gaged w~ he s~3bs~rat~(s), sald slLrface~s3 being coated a~ least ~s p~ with a layer of a ~ealant: havi.ng dispersed ~herei~s a ~ lat~ i~ller, s~ 1Eler b~~g a~apte~ to bite i~to the subs~ra~e(a) on reco~ery of the memo:ry me~al member(s~r q~he ~pxe~;ent ~ 3ntlo3~- urth~r pro~i.des a method of c:o~nectlng æ de?~ic~ to at lea~ o~e subs~ra~e which comprlses pos~ioni~g a~. lea~t o~e sur~ce of th~ ~e~ice ad3ac~3nt the sub~ate(s) w~s a la~er o~ s~a~ nl~ osa~ therebe~ween, said seala~t h~ri~g di~3per~;~d ~here~ a pæt~culate filler, ~ro~id~ng at Ieas~ on~ heat-recoYerable memory met~l member adapted o~
r~co~ery ~o cause ~aid surface (~ of th~ device to be sealingly engaged with the substrate(s) and the filler to bite into the sub-strate(s) and heating the heat~recoverable member(s) to cause recovery thereof.
The present invention still further provides a method of joining a member to at least one substrate, the to-be-joined sur-face of said member being composed of a first material and the to-be-joined surface of said substrate being composed of a second material, which method comprises (a) positioning said surfaces adjacent to each other; (b) providing between surfaces a layer of an adhesive composition, the adhesive composition being softenable by heating and comprising a polymeric phase having dispersed therein a particulate filler, said filler having an aspect ratio less than 2 and having a hardness greater than at least one of said first and second materials at a temperature at which said :. adhesi~e composition is softened; (c) providing a member which is heat-recoverable and is composed of a me~ory metal and which, when it is heat-reco~ered, causes said surface composed of a first material to contact said surface composed of a second material through said layer of adhesive c~mposition; and (d) heating said : 20 adhesive compos~t~on to a temper~ture at which ;t is softened and heating said heat~recoverable member to cause recovery thereof, thereby forcin~ said surfaces into sealing contact with each other and causing localized deformation of at least one of said surfaces by sa;~d particulate filler.
The present in~ention also provides a method of joining a member to at least one substrate, the to-~e-joined surface of said -~ member being composed of a first material and the to-be-joined surface of said substrate bein~ composed of a second material, ' ~ `

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which comprises: (a) placing a first member which is not heat-recoverable adjacent said substrate, the surface of said first member adjacent said substrate being composed of a first material and the surface of said substrate adjacent said first member being composed of a second material; (b) providing between said first member and said substrate a layer of an adhesive composition being softenable by heating and comprising a polymeric phase having dis-persed therein a part~culate filler, said filler having an aspect ratio less than 2 and having a hardness greater than at least one of said first and second materials at a temperature at which said adhesive composition is softened; (c) positioning a second member adjacent said first member, said second member being heat-recover-able and being composed of a memory metal; and (d) heating said adhesive compos~tion to a temperature at which it is softened and heating said second member to cause recovery thereof, thereby forcing said first member into sealing contact with said substrate and caus~ng localized defoxmation of at least one of said substrate and said first member by said parttculate filler.
Preferably the dev~ce includes at least one non-heat-recoverable member, which i5 preferably plastically deformable~ a surface of which is adapted to engage the substrate~sl, the heat-recoverable member(s) acting as a dri~er to urge the non-heat-recoverable member(s) and the substrate(s~ into engagement.
In one preferred form of the invention, the device is in the form of a fluid-tight coupl;~ng adapted to couple a plurality of pipes, particularly soft metal pipes, such as copper or alum~nium.
In such preferred form, a hollow non~heat-shrinkable "tubular"
member ;s employed having the appropriate number of inlets and - 3a -outlets for connection to the pipes to be coupled (~he term "tubular" is employed herein in a broad sense to include members of irregular and/or varying cross-section, Y-shaped, T-shaped and X-shaped members and members having one or more closed ends and is accordingly not limited to r~ght cylindrIcal members). For example in the case where a pair of aligned pipes are to be ~oined, then a generally linear tubular non-heat-recoverable member is conveniently employed together w~th a memory metal member also of tubular form and coaxially disposed about the non-heat-recoverable member.
In a second prefe~red fo~m of the invention, the device is in the form of an electrical connector for a plurali~ty of electrical conductors, e.g. copper or parti~cularly alum;~n~um, especiall~ high voltage conductors such as ~us-~ars ~n electrical switch gear. In such form, a plurality~o~ non-heat-shrinkable shell members are provided adapted to be positioned about the ends of the conductors to form a generally tubular connect~on assembly~ ~urthermore, a plurality of heat-recoverable memory metal members in the form of bands or rings serViny as dr~vers are also pro~v~ded, each driver ~eing adapted to be positioned a~out the connection assembly at or adjacent to an end thereof so that recovery of the drivers will cause the conneat~on assembly to grip the conductors securely.
; Electrical connectors illustrat~ve of the type to wh~ch the second preferred form of the lnvention relates are disclosed in co-pendi`ng Canadian Patent ~pplication No. 341,384, filed December 6, 1979, The eho~ee of sealant w-ill depend on the nature of the ; applieation~ In the case of p~pe couplings where, ~n use, high pressures are substa~ned and the pr~me consideration IS hIgh shear '7~

strength, then preferably the sealant comprises an adhesive, and partieularly an adhesive which is taek-free and solid at 25C and softenable on heating so that on applieation of heat to cause heat-reeovery, the adhesive will simultaneously soften and flow.
Of particular interest are such adhesives which are also -thermo-setting and undergo a ehemical transformation on heating, e.g. by a eross-linking ~ 4a -' ' ' . ' ' ~
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- S - MP2 ~7 reaction, se:~ing to enhance or create the adhesive properties of th adhesive after cooling.. Particularly good resulis ha~e been obtained employlng epoxy resin systems.

Suitable cu::able epoxy resi:~ls lnclude resins whi ch compr~se 5 to 95 parts by w~ight o~ an eps:xy resin, havi~g an epoxy ~quiYalent weight o~ 100 to 5,5:~0, preera}~1y 600 to 800~
e..g. a. bis~?henol A epo2y resin, 5 to 95 parts by w ight c:E
arl epoxy res:in with at least 4 functional sitesr e.g. a cr~ novolac resi;~ ha~ring arL epoxy e~Euivalent weigh~ of 200 to 500t a~d a ~ubsta~tially s~oichiome.tric amc~unt of a cur~ age~t, ~g. a ~?henolic: re~in, pre~erably a bisphenol ., .
A ~ymer with z. molecular weigh~ o abou~ 50~ a~ a~hydride, a~ amine or a~ amide~ I~ order to impro~e ~:ha flex~ility o ~:he epo~ resi~ compos~tlon a;f~er cu~ g, ~h~ compos~io~
may s:o~tairL a; s~Qall amou~t~ e.g~ ~ to 209~ bS~ weigh~ of a car~oxy-te~a~:ea butaaie~e-nit~ile rubber which will :r~eact ~ - *~a~de^ reæ~ o g~e.a cr.~ss~ kable g:raf~ copolymer re~i~.. The rubber pre ~rably has ~ moleculax weight of 3tOQO- to 4too0r e-gO about 3,500, a percsn~ nii con~
of 10 ~ 27~ ou~ ~8~ a~d . carboxyI ~anctionality o~ t~: 3 p~r moIe~le" e~q, abou~ 2 p r ~Iecule~ Whe~
usi3~ s~lch. cura~le ~y~tem~ heat~g should be co~tinued or Ei;l::ient ~ime a~eæ ~e adhesi~e has. ~:Lowed ~o pro~id~

~e d~ ed degr~e.o:E c~.~;, Fcr exampl~ ~or arl ~poxy resi~
sy~tem, heatl~g for up to: 3 mi~ute~ at 150 to 25ac ge~erally sui~abl~.

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In the case of electrlcal connectors where the prime consideration is a good electrical connection by penetration of low-conductivity or non-conducting surface films on the conductors to be connected, especially tough oxide layers, e.g. in the case of aluminium conductors, then any sealant may be employed that prevents re-establishment of such surface layers, e.g. a sealant to exclude oxidative influences such as oxygen. For electrical use, the sealant employed is preferably electrically conducting.
The sealant may be a viscous mastic or may be non-flowable after installationl e.g. of the type hereinbefore described in relation to pipe couplings and preferably rendered electrically conducting by the inclusion of conducting fillers in manner known per se.
The sealant composition is prefera~ly coated on the surface(s~ of the member which is to contact the substrate, but ~ it may be provided at the interface in any convenient manner, for - example as a coating on the substrate(s). The initial thickness of the sealant co~ting i.e. before installation of the device is preferably 0.25 to 3 mils, especially 1 to 1.75 mils. The thick-ness of the sealant coating after xecovery of the memory metal member w~ll be substantially less, for example, less than 0.25 mil, typically a~out 0.1 mil. Preferahly at least one of the surfaces which contacts the sealant is treated to improve wettability by the sealant, e.g. to improve adhes-ion when and adhesive is employed, e.g. by sand-hlasting.

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- 7 - 1~P28 7 ._ It is important, iI~ order.. to achieve the o~jectives of the present i~vention, that thè particulate f iller should cause looalized deormation of the substrate (s) and preferably als~ the surface (s) o t}~e de~rice which engages ~he substrate (s), when the surface(s) and the substrate(s) are caused to engage, with the sealant, e. g .. the hea~-so~e~ed adhesive co~positio~, betwee~ the surface(s~ an~ the subs~rate(s).
In: the case where shear strength 15 c~ p~ne importance a~d arl adhesi~e is ~E?lc~yed, after ins~allatioIl o~ the d~vice at which stage the adh~3si~Te is. ~ ~he solid st te, the i~iller partic:les pro~ride a plurality o:E anchors between the adh2siv2 ~ al~ leas1: orl~ of th~ a~jacent suraces, ~hus improvin~
th~ shear strength o~ the bond between the surfaces.. :I?artic~larly go~d results are obtain~d i~ i~idual particles of ~he ll2r ar~ partlalIy ~ribedded in bo~ adjace~t surfaces, thu~. ors~i~g a locking bridge b~tween them. For ~his reason, ; preferred. that the ~iller should comprise pa~icles havi~g a~ ast one Ii~ear dime~sion greates than 0.05 mil, pre era~ly greater than O . l mil. On the o~her ha~d, the e~cte~t ~ a~railable recove~ the h~a~recoverable mel;ber (~a ~ som~ cases the me~hod us~a to fo~ ~he layer of aahes:L~Q com~?o~3itio~) li~i.~ maxi~num size of the iller article~, whlch are, the:~efore/ preferably less than 5 mi.ls iD ~m~ l~ear dimer~ion~

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~ 8 - MP287 I~ the case where a satisfactory 21ectrical co~nec~ion is the prime consldera~ion, then the ~iller particles after ins~alla~ion o~ the de~ice should ~e such as to penetrate the surface layers, e.g~ oxide layers, on tha conductor. It is/ however, preferable to take ad~antage o th~ high shear stren~th aspect of the present inv~n-tion also i~ .he case o --electrical Gonnec~ors and accordingly filler particle dime~sions as hereinbe~ore defined are pre~erably also amployed ~or elec~rical use~

~refera~ly the ~iller pa~ticles ha~e a~ aspact ratio of less than 2 to pr.o~de ~he deslred d2gree anohoring or suxac~
Iayer pe~ratio~

The ~illers ~mployed in ~he prese~t in~tio~ should b~ such as ~ bit~ in~o ~he ~ubs~rate(s) and preerab1y also the e~gaged surface~s) ~f ~he de~ice~ To this end-; the hara~ss n~mber ~ ~he fllle~ s~ould be ~gr.~tes tha~ that of ~he su~s~rate(s) ~d preferably also ~he engaged surfac~(s) ~f the device. ~pprop~ia~e filler5 have be~n ou~d to b ~o~ga~lc ~1l1ers ~uGh as quartzJ alum~na and o~her ceramlcsr glll~o~ ~arblde and metals. such as ~ic~ For electrica use~ conduG~s fllle~ such as me~als7 particularly ni~kel~
or ~il$co~ car~ide are approprlate~
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~he a~ou~ o~ fill~r pres~t i~ th@ seala~ is preferably 10 " J
to 50 weighk ~ of ~he ~otaI ~ealant sy~t~ffl9 more pre~Prably 20 to 40 wetght ~, e.g. abo~t 30 weight per cent.
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_ g - MP287 When a non~heat-rPcoverable me$~er is used in addltion to the heat-reco~era~le member, it should naturally hav~ a melt:Lng point substantially greater than any te}nperature reached duri:ng ~stallation, e ~, g . abo~e 300C, pre:Eerably above 5t:)0C, ~d it is preera~1y composad o a metal or a c:omposite matarial of s~ilar properties~ As herein~e:i~ore e~lai~ed lt is also preferable that it should ulldergo plastic de~o~ation as a result o recovery of the heat-reco~erable m~mber. In a ~rPferred arra~gemen~: which result~: in ~uch defor:mation a2ld whlch is. suita~le for use wi~:h. tllbular subs~rates,. ~he na~-hea~-recovera:b1e mem~er whioh is pr~fexab1y composed a~ a me~ .1, is i~ the form oi~ a tu~e ar~g the memory metaI member is i~ the ~or~a- o a radially heat-recoverab1e ~ub2 whit:h iS~ l?Qsi~i.oned co-axlally ~ith a~& a~j:acent to th~ no:~-hea1~-r~co~rerablQ meml:er.,. The mem~ry me~al m~er i~ pre~erab1y hea~-sh~inkable and is placed around the noII heat-recove::able member~ Tha s~l~îace ~ r~ca~er~1e- ~er r~em~te :com the memory meta1 member i~ gen~3rally smooth, but it may compris~ radial tf~ n th0 ~orm o a~ula~ r~g~ whi h ~ubse~uen~ly ~gage tha ~bstrates. It:: ~hou1d~ how~7eE, be nc)ted that if such t~el~ pr~sent/ i~ ~erally Iae~ Q5S~ :or the adhesi~e , . compos1~ioQ to b~ coate~ re1~t1ve1y thi~ly, or ~ot at~ all, . ~ ..

o~ ~he edges o th~ teeth.. This is becau~e the~ t ~f ra~ial aeformatiorl. ~hich. a~a b~3 pro~i~}ed by the ecoIld m~3mbe~ i~ 1i~ ted~ The ~lo~-heat-reco~rerable a~d memory m~ta1 members.and tha substrates are pref~rab1y o~ annu1ar .

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cross section. Often their cross-sec-tions will be substan-tially the same through-out their length. However, where substrates of different outer diameters are being coupled toge-ther, at least the inside diameter of the inner member may have a stepped configuration.
Part or all of the exposed surface of the non-heat-recoverable member may have a coating thereon of a thermochromic paint to indicate when it has been heated to a certain temperature, in order to provide a guide to the temperature reached by the adhesive composition when a heat softenable adhesive is employed.
Alternatively the softenable adhesive composition itself when employed may, incorporate a thermochromic paint and be applied so that part of it is visible when the heat recoverable member is recovered.
The memory metal member is preferably composed of a memory metal which has (either inherently or as a result of a pre-treatment) an A (austenite start) temperature above 40C, e.g. 40-150C., so that it can be stored at room tempera-ture and so that recovery thereof and, when a heat softenable adhesive is emplo-yed, softening of the adhesive composition, can be effec-ted in the same heating operation. ~otable results are obtainable using members composed of ~-brass, as disclosed for example in commonly assigned United States Patents 4,144,104;
4,146,392 and 4,166,739. The heat-recoverable member, after it has recovered, generally remains in position, but when it is used to effect plastic deformation of another member which contacts the substrate, it can in some cases be removed once it has efEected the desired deformation of the other member. When it is to ; remain in position, it is preferably composed of a memory metal whose normal A
temperature is below room temperature but which has been pre--treated so that its initial A temperature is above room temperature (20C) - for example by the method disclosed in commonly assigned United States Patent 4,095,999. On the ; other hand, if the first member is to be removed, then its transformation tem-, - 10 -~ ''~'`
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perature is preferably above room temperature.
When a non-heat-recoverable member is used in addi-tion to the heat-recoverable member, it will generally he -the same length as or shorter than the heat-recoverable member. As hereinbefore explained however -there may be two or more heat-recoverable members which are the same or different and which exert force on different parts of the non-heat-recoverable member, as for example two cylindrical heat-recoverable members.
As hereinbefore described, the invention is particularly valuable for coupling together substrates, especially pipes, made of soft metals such as alumi-nium or copper, particularly thin-walled pipes e.g. of wall thickness such that the ratio " :

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- ~2 - 1~P287 w/d, where w is the wall thickness and d the outer diameter, is less thar. O.lS, e.g.- less than ~.1, generllly a wall thickness le~s than 100 mils, e~g. 20 ~o 50 mils, of the kind widely used i~ re~riyera-tion and air-conditioning equipment. Such pipe~ will normally have an outer diamet~r of 0025 to I0~ inch. The substra~es to be c~upled together may be of the same or differen~ materials and o the same or differen~ dimensions.. Where a non-heat-recoverable m~mber is used i~ additio~ to the heat-recoverable member, it is preferably composed o the 5am~ m~al as ane or bot~ o~ the plpe~:to ~ ~o~ed_ Il is pxeerred that.a su~sta~ially u~o~ ~ressure should be exert~d o~ ~h~ subc~rate by the co~tac~ln~ surac~

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Em~odiment~ o~:th~ present in~e~tion w~}~ ~ow b~ described ~- wi~h re~re~ce to th~ accom~ g arawi~gc wh~rei~;

Pi~u~ -pl~ w.t ~ ly i~ cross-section, of a coup11ng membeæ o the in~ention in position, prior to r~c~ery~, around t:W9 tt~}~es to be coupled tog~ther, Figur 2 15 a cro~s0sectio~ o~ lln~iAA o~ Piqure It - ' .
Fi~re 3 is a cros~-se~lon o a part of the interface : . . he~w~e~ ~he coupll~g m~mber and one of the 1~.' d ~u~e~, ater ~ecove~y of th~ coupling; and : .
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1 3 - L~!IP 2 ~ 7 F:igure 4 is a plan view, l~artly ln cross-sectlo~ of arlother coupling member o the in~ention in positiorl, prlor to recovery, around two tube~i to be coupled together .

Reerrirlg ~o Fi.gures 1 and 2 o the dxawlngs, two pipes 5 and 6 ara shown which are to be coupled together by means of a coupling meml:~er wh~ch comprlses a tubular plas~ically d~ormab1e member 1 and a heat-shrinkab~e -~ubular mem~er 2.
Th~ de:~ormable member ~ has a coating o an adlhesive composition

3 on its. inslde sur~ace~ Adhesi~re c~mpositlon 3 comprises a par~ially cured epox~ resirL a~; about 2096- by weight, based o~ the compo~ on, o:E qua~tz partic:les_ ~e end portions o th~ out:er sur~ac~ oi~ ~he de0~2lble m~er 1 ha~7e a coating 4 ther~ oi~ thermochromic paint :- Figure 3 shows the l~eraca b~ween the pip~ 5 ar~d the de~ormable me~er-1~ a'cer the a~sembly shs~ L i~ Flgures 1 and 2 has beP:}l ~ea~ted t~ ~ rec:o~:r~ of- m~r 2 ~:L~ m~lti~g and curing of ct~mpos~ tio~ 3. Quartz particles 33 in the adhesi~e co~po~itio~ ~ha~e bec~ embedd~d i~ }: oth surf aces . Figure shows heat-shr~nkable ~ubular mem~er 2 ha~vi~g a coati~g 3 o~
it~ sid~ surface an~ part of its ou~ide ~ ac~ o: a~
ad:hesive c~mpositlon a~ just descriJ~ed, in po~it~on around pipe~ S a~d 6 whic~ are to b~ coupled together.

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- 14 ~ ~ 287 The adhesive composition employed abo~e and whlch is suitable or ~owdex coating wa~ prepared by classifying a milled compo~ition co~taining:

Parts b Bisphenol A epoxy ~esin of ep~xy 38 equi~a~ent weig~t about 750 ~"Epo~J2001") ~ul~i~c.tio~al epoxy c~esQ1 ~o~u~ac 4.25 resi~ o~ epoxy equivalen~ weigh~
a~out.230 ("~CN 1280'') Bisphe~ol A polymer curing age~t 17.75 o~ colacul ~ welgh~. about 500 ("æ~ 8062;~0L") ~ ' ~; : *Quartz particle~ ~np Quartæ" ) 20.00 Ti~2 Carb~ Blac~ (S~atex 160) 0~
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*The par~icle si2e distribu~ion o the qu~rtz particles was , ~ ~
as~ollows:

R ~ al~d ~y 80~. mesh scre ~ O % by weight R~tained by l~0 mesh cr~en 0.
eta~ned by 120 m~-~h scr8e~
talned b~ l40 mesh scr~e~ . 0.9 R8~a~n~d.by 160 m~gh scree~ 0,7 ; ::
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~, - 15 L~ 2 8 7 Re~aill~d by 200 mesh sereen 3.3 Retairled by 270 m~sh scre~Qn 5 . 9 Re~ained by 325 mesh screen 8 ~ ~
Pass ~hrough 325 mesh gcre~n 80. 2 Th~ classi;Eied composition wa~ applied by ~owder ~oating to th~ pre~riously sandoblasted i~terior surface o a right cyli~drical co~per tu}~e of ~nner diameter 0 . 764 ~ ou~er diameter o.848 inch and le~gth 1.5 inch, the exterio~ o the tube bei~g masked b~ a: t~e of poly~thylen~ which had heen heat-shrunk arour~d it.. Th~ coated tube was heated suf:f~iciently to cause the particles c~ the adhesi~re co~posi~to~ to co~lesce and f.orm. a la~er ~bout 2 mils thick. The maskin~
-- tub~ o }~olyethylene was then: remo~red~. .

A rad~ally heat-shr~nkable rlgh~ cyli~drical. ~ ha~ing .
a ~erlgth of 1.2 lnc~L an exter~al d~ameter o~ 1 l~ch and `~sal ~ust ~ a.:8~8--~c}~ ha~ it was a close toler~ce ~it ov~r the copper ~u~e~ blas made by- radially expandlng a tube of a ~:-b~ass which had beers cooled ir~ liquid nitrogen.
brass had b~ tr~a~ so ~hat i~ ha~ 5 o about 40~-~ 50~C.. Th~ heat-shrinkab~:e ~-bras tube wa~ r~no~ed xom ~h~ ll~ld ~ ogen ~d placed celltrally oYer t~e ocpper tu~e, which wa sui~iciently strong to resist arly radial s}~ kage ai~ bra. ~ ~e under normaI ~orage cs:~ditions.

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- 16 - ~287 The ends of two cc: pper tubes of outer diameter 0 . 7 5 irlch and wall thickness 35 mils were placed with~n the adh~sive-coated copper tube in the mar~er shown in Fig~e 1. The asse~bly was then hea~ed to a tem~erature of about 200C for about 1 mirlute to cause recovery of the ~-brass tu~e a~d melting and subsequent c~ring o the epoxy resin composi~ion.

The coupling produced in ~his was was very s~rong, ha~r~ng a pull-au~ s~rength greater tha~ 1,000 psi a~ room temperature an~ ?tt 150C ~nd beiny capable oi~ holding an intarnal prPssure o~ 3~000 psi a~ room temperature and~ at 150C.

Similar results we::a a hieved when. usi~ ~ aIumini~ tube i~s~ead o~ ~:h~ copper ~be ir~. the coupl~ng member, i3nd wher~
reI?lacir~ one or bo~h o the copper tube~ to be joined by alumini~m tube~ o~ th~ same dimensions~.

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Claims

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

1. A device connectable to at least one substrate which comprises at least one heat-recoverable memory metal member adapted on recovery to cause at least one surface of the device to be sealingly engaged with the substrate(s), said surface(s) being coated at least in part with a layer of a sealant having dis-persed therein a particulate filler, said filler being adapted to bite into the substrate(s) on recovery of the memory metal member(s).

2. A device according to claim 1 wherein the sealant is an adhesive.

3. A device according to claim 2 wherein the adhesive is softenable on heating.

4. A device according to claim 1 wherein the adhesive is a thermosetting adhesive.

5. A device according to claim 4 wherein the adhesive is a curable epoxy resin.

6. A device according to claim 1, 2 or 3 wherein the thickness of the sealant before installation of the device is in the range 0.25 to 3 mils.

7. A device according to claim 1, 2 or 3 wherein the thickness of the sealant after installation of the device is less than 0.25 mils.

8. A device according to claim 1, 2 or 3 wherein the aspect ratio of the particulate filler is less than 2.

9. A device according to claim 1 wherein the hardness number of the parti-culate filler is greater than that of the surface(s) of the device and the sub-strate(s) to be engaged.

10. A device according to claim 9 wherein at least some of the individual filler particles, after installation of the device bite into the surface(s) of the device and the substrate(s) to form locking bridges therebetween.

11. A device according to claim 1 wherein the filler comprises particles having at least one linear dimension thereof greater than 0.05 mil.

12. A device according to claim 11 wherein the filler comprises particles having at least one linear dimension thereof greater than 0.1 mil.

13. A device according to claim 1, 2 or 3 wherein the filler comprises quartz, alumina, silicon carbide or metal particles.

14. A device according to claim 1, 2 or 3 where the amount of filler in the sealant is between 10 to 50 weight per cent of the total sealant system.

15. A device according to claim 1 including at least one non-heat-recovera-ble member, at least one surface of which is adapted to engage the substrate(s), the heat-recoverable member(s) acting as a driver to urge the non-heat-recovera-ble member(s) and the substrate(s) into engagement.

16. A device according to claim 15 wherein the non-heat-recoverable mem-ber(s) is plastically deformable.

17. A device according to claim 15 wherein the non-heat-recoverable mem-ber(s) is a metal.

18. A device according to claim 15 including a non-heat-recoverable member of tubular form.

19. A device according to claim 18 including a radially heat-recovery mem-ory metal member of tubular form co-axially disposed about the non-heat-recovera-ble member.

20. A device according to any one of Claims 15 to 17 including an assembly of non-heat-recoverable members, the assembly being of generally tubular form.

21. A device according to any one of Claims 15 to 17 including an assembly of non-heat-recoverable members, the assembly being of generally tubular form, and including a plurality of radially heat-recoverable rings or bands, each ring or band being positioned at or adjacent to an end of the generally tubular assembly of non-heat-shrinkable members.

22. A device according to any one of Claims 1 to 3 wherein the heat-recoverable member (s) comprises .beta.-brass.

23. A device according to any one of Claims 1 to 3 including a thermochromic paint to indicate when sufficient heat has been supplied for proper installation.

24. A device which comprises a member which is heat-recoverable and is composed of a memory metal and which, when it is heat-recovered, causes movement of a surface of the device which has a coating thereon of an adhesive composition, the adhesive composition being softenable by heating and com-prising a polymeric phase having dispersed therein a particulate filler, said filler having an aspect ratio less than 2 and having a hardness greater than said surface at a temperature at which said adhesive composition is softened.

25. A method of connecting a device to at least one substrate which compri-ses positioning at least one surface of the device adjacent the substrate(s) with a layer of sealant interposed therebetween, said sealant having dispersed therein a particulate filler, providing at least one heat-recoverable memory metal member adapted on recovery to cause said surface(s) of the device to be sealingly enga-ged with the substrate(s) and the filler to bite into the substrate(s) and heat-ing the heat-recoverable member (s) to cause recovery thereof.

26. A method according to claim 25 wherein the device is as defined in claim 1, 2 or 3.

27. A method according to claim 25 wherein the device is connected to a plurality of substrates serving to connect the substrates one to another.

28. A method according to claim 27 wherein the device is connected to a plurality of pipes providing a fluid tight coupling between the pipes.

29. A method according to claim 28 wherein each of the pipes has a wall thickness, w, and an outer diameter, d, such that w/d is less than 0.1.

30. A method according to claim 29 wherein the wall thickness is 20 to 50 mils.

31. A method according to claim 28 wherein the device is connected to a plurality of electrical conductors and provides an electrical connection between the conductors.

32. A method of joining a member to at least one substrate, the to-be-joined surface of said member being composed of a first material and the to-be-joined surface of said substrate being composed of a second material, which met-hod comprises:

(a) positioning said surfaces adjacent to each other;

(b) providing between surfaces a layer of an adhesive composition, the adhesive composition being softenable by heating and comprising a polymeric phase having dispersed therein a particulate filler, said filler having an aspect ratio less than 2 and having a hardness greater than at least one of said first and second materials at a temperature at which said adhesi.ve composition is softened;
(c) providing a member which is heat-recoverable and is composed of a memory metal and which, when it is heat-recovered, causes said surface cornposed of a first material to contact said surface composed of a second material through said layer of adhesive composition; and (d) heating said adhesive composition to a temperature at which it is softened and heating said heat-recoverable member to cause recovery thereof, thereby forcing said surfaces into sealing contact with each other and causing localized deformatlon of at least one of said surfaces by said particulate filler.

33. A method according to claim 32 which comprises:
(a) placing a first member which is not heat-recoverable adjacent said substrate, the surface of said first member adjacent said substrate being composed of a first material and the surface of said substrate adjacent said first member being composed of a second material;
(b) providing between said first member and said substrate a layer of an adhesive composition, the adhesive composition being softenable by heating and comprising a polymeric phase having dispersed therein a particulate filler, said filler having an aspect ratio less than 2 and having a hardness greater than at least one of said first and second materials at a temperature at which said adhe-sive composition is softened;
(c) positioning a second member adjacent said first member, said sec-ond member being heat-recoverable and being composed of a memory metal; and (d) heating said adhesive composition to a temperature at which it is softened and heating said second member to cause recovery thereof, thereby forcing said first member into sealing contact with said substrate and causing localized deformation of at least one of said substrate and said first member by said particulate filler.