GB1600612A - Repairing metal parts - Google Patents

Description

PATENT SPECIFICATION

( 11) 1600612 ( 21) Application No 26327177 ( 22) Filed 23 June 1977 ( 23) Complete Specification filed 31 May 1978 ( 44) Complete Specification published 21 Oct 1981 ( 51) INT CL 3 C 08 K 3/10 ( 52) Index at acceptance B 3 V X 6 C 3 B 1 C 1 1 C 221 C 33 A 1 C 6 X 1 D 2 C 1 L 2 CX N C 3 R 32 KH C 1 C 22 C 33 A C 6 X L 2 CX C 3 Y B 320 B 321 B 329 G 200 H 800 ( 72) Inventor CHRISTOPHER ROBIN STACK McDONNELL ( 54) REPAIRING METAL PARTS ( 71) We, BELZONA MOLECULAR METALIFE LIMITED, formerly known as METALIFE MOLECULAR BELZONA LIMITED, of Claro Road, Harrogate, North Yorkshire, HG 1 4 AY, a British company, do hereby declare the invention, for which we pray that a patent may be granted to us, and the mthod by which it is to be performed, to be particularly described in and

by the following statement:-

This invention relates to method of repairing metal parts using hardenable resin compositions and especially, although not exclusively hardenable resin compositions which require a separate catalyst or hardener to be added to them in order to produce a hardened resin.

According to the present invention there is provided a method of repairing metal parts comprising replacing worn or damaged portions of metal in said parts with a composition comprising a liquid-polymerisable resin and a hardener for said resin, said composition also including a filler to impart metallic characteristics, said filler being a ferrosilicon.

The liquid resin is preferably a resin of one of the following types: epoxy, polyether, saturated polyester, polyol, isocyanate, polyamine, polyamide, polymercaptan, silicone, unsaturated polyester, acrylate and methacrylate More preferably the resin is an epoxy resin.

Preferably the silicon content of the ferrosilicon is from 10 to 80, more preferably to 20 and most preferably about 15 parts by weight per 100 parts by weight ferrosilicon.

Preferably the ferrosilicon is present in an amount of from 250 to 350 parts by weight per 100 parts by weight of resin.

Preferably the composition also includes silicon carbide in an amount of from 40 to parts by weight per 250 parts by weight ferrosilicon.

Preferably the composition also contains a silane as wetting agent in an amount of from 0 5 to 1 5 parts by weight per 100 parts by weight of resin.

The present invention also provides a two component pack, comprising a first component including a liquid polymerisable resin and a second component including a hardener for said resin, one or both of said first and second components also including fer 55 rosilicon.

Preferably the composition is obtained by mixing the two components of a two component pack, a first component including a liquid polymerisable resin and a second 60 component including a hardener for said resin, one or both of said first and second components also including ferrosilicon.

Two component synthetic resin based compositions are widely used as repair mat 65 erials throughout industry Applications for these products include repairs to, and rebuilding of pumps, valves, engine blocks, cylinder liners, hydraulic rams, keyways, bearing housings, castings, shutes, hoppers, 70 shafts, machine beds, condensers, sumps, transformers and many other applications.

These synthetic resin based compositions normally consist of a base component and a solidifier component which when stored 75 apart have a shelf life of months or even years On mixing the two components together however in a predetermined ratio, a chemical reaction occurs in the form of polymerisation yeilding a product with 80 totally different physical characteristics from the original components This polymerisation reaction varies considerably, according to the chemical nature of the components involved The reaction time for 85 example can be as short as several seconds for certain cycloaliphatic Epoxy based compositions and as long as several days for composition involving long chain polyamide resins Likewise, the physical properties of 90 the end product from this polymerisation.

can vary from hard brittle polymers to extremely flexible synthetic rubbers.

The resin types involved in formulation; these compositions can be broadly classified 95 into Epoxies, Polyurethanes, Unsaturated Polyesters, Silicones and Acrylics, although the present invention is not intended to be limited to any particular class of polymer or resin 100 z 0 1 600 612 Within each classification there are numerous variations according to the individual components involved Epoxy resin based compositions for example will always involve a molecule containing more than one a Epoxy group (whether situated internally, terminally, or on cyclic structures).

The solidifier component can vary however from simple amines such as diethylene triamine to complex polymercaptans Similar variations can be described for polyurethanes, unsaturated polyesters, silicones and acrylics With each type however two components are involved to produce the end polymer.

Mixing these components together will produce a polymer with physical properties such as adhesion, hardness, flexural strength, impact resistance, compressive strength, heat resistance, abrasion resistance etc The individual components possess none of these properties and could not be considered as repair compounds in the meaning of this particular patent The resultant polymer however, after mixing, possesses all the above properties to varying degrees The individual properties can be varied according to the nature and the type of resin employed For example from Epoxy resin based compositions cured with amine solidifiers, polymers with outstanding hardness and compressive strength can be produced The same Epoxy resin based composition cured with a polyamide solidifier can produce a polymer with outstanding adhesion characteristics By careful selection of base and solidifier components, polymers with outstanding adhesion, impact resistance, flexibility, flexural strength etc.

can be produced.

In addition to variations in the type of resins used the components discussed in this patent application can be reinforced with numerous fillers Fillers such as asbestine, talc and china clay can be incorporated to improve adhesion Asbestos and fibrous type fillers give improved impact resistance, whereas metallic fillers give rise to improved abrasion resistance and with careful selection of the filler involved a metallic filler can impart certain metallic characteristics to the polymer.

The vast majority of applications for two component resin based repair compounds involves the repair and reclamation of Iron and Steel based machinery and equipment, where erosion, corrosion and abrasion play a major part in the breakdown and failure of this equipment throughout industry Erosion in the form of abrasion and corrosion causes premature failure of pumps, valves, liners, bearings etc Repair of these breakdowns with the two component compositions discussed above is well known and widely practised The abrasion resistance of these compositions is extremely limited however, and for this reason Iron powder is widely used as a filler for these resin based compounds The use of Iron powder at high levels produces a polymer with many 70 characteristics of the parent metal These compositions are strongly magnetic and can be drilled, tapped and machined like conventional metal In addition the abrasion resistance of Iron filled polymers is consid 75 erably better than the same polymer without this metallic filler.

The same powder however does have a number of drawbacks which must obviously be weighed against the above advantages 80 when formulating a metal repair composition In particular, polymers filled with a high level of Iron powder will rust very readily when exposed to the atmosphere and the following example (Example I) illustrates 85 this.

The liquid resin from the reaction process between 2 2 bis ( 4 hydroxyphenyl) propane and epichlorohydrin was blended with 100 mesh (British Standard series) Iron powder 90 in the ratio 100 parts liquid resin and 300 parts Iron powder by weight The addition of 50 parts by weight of a liquid Amidopolyamine resin gave a composition which polymerised over a period of 24 95 hours The resultant polymer was exposed in the ASTM B 117 Salt Spray and showed considerable rusting after only 50 hours exposure.

On natural exposure in an industrial envi 100 ronment the same composition shows a similar degree of corrosion after only 2 weeks exposure.

The use of Iron powder in a two component synthetic resin based composition will 105 also lower the chemical resistance of the resultant polymer Metallic Iron is readily attacked by a wide variety of industrial chemicals including many acids and alkalis.

Iron filled polymers as metal repair com 110 positions therefore exhibit most of the disadvantages of the component they are repairing Whilst this does not preclude their use as general purpose repair compositions it does means that the repair has a 115 limited life The abrasion and corrosion found in pumps for example will containue to attack the repaired area and frequent recoating will be necessary.

Metals other than Iron powder have been 120 used as fillers in these polymers but invariably the use of alternative metals can lead to numerous side effects such as low abrasion resistance, bimetallic corrosion, machining difficulties and storage problems Iron pow 125 der presents none of the above problems and of course produces a compositions with similar characteristics to the repaired surface.

Work on alternative powders to Iron has 130 1 600 612 lead to the examination of a unique alloy of Iron and Silicon under the name of Ferrosilicon This alloy is produced in Electric Arc Furnaces by melting suitable mixtures of Iron filings or oxides with crystal SilicaQuartz, Quartzite and Coke The resultant Ferrosilicon is then broken down in two ways.

a By grinding The liquid Ferrosilicon is allowed to cool and then broken up, ground and sieved until the required fineness is achieved.

b By atomising This involves atomising the liquid Ferrosilicon with air or steam.

The fine powder created is then quenched in water, dried and sieved to the required fineness.

These two different processing methods produce powders with different characteristics The powders produced by the atomised process are generally spherical in shape, with the surface of the individual grains passivated by a thin oxide layer This results in a powder with outstanding corrosion resistance.

Granular Ferrosilicon however has a comparatively rough surface and the sharp corners and edges of this powder can give rise to corrosion under agressive conditions.

Both powders are available in fine and coarse grades.

The Silicon content of the Ferrosilicon alloy can be varied according to the levels of Iron and Quartz used in the manufacturing process In practice 15 %, 45 % and 75 % Silicon levels are used and the conventional outlets for these alloys are as follows:Heavy media separation 15 % Ferrosilicon is widely used for treating Iron, Manganese, Chromium, Lead and Zinc ores with separation occuring into waste material and preconcentrate.

Electrode coatings in coating Electrodes, Silicon is used as a reducing agent, to brine the Silicon content in the weld Ferrosilcon (with 45 % Silicon) is widely used as the Silicon carrier in these coatings.

As an alloying material with this end application Ferrosilicon with Silicon contents as high as 75 % is used as an alloying material in Steel Mills and Foundries.

These end applications, particularly the Heavy Media Separation process, call for a powder with high corrosion resistance and Ferrosilicon meets this requirement This property of corrosion resistance together with the fact that Ferrosilicon exhibits many of the properties of Iron powder, the powder is magnetic and can be machined, trapped and drilled in a similar manner to Iron, led to an investigation into the suitability of this alloy as a replacement for Iron powder in two component metal repair components.

The initial investigation consisted of the following work The liquid resin from the reaction between 2 2 bis ( 4 hydroxyphenyl) propane and epichlorohydrin was blended with 100 mesh Ferrosilicon in the ratio 100 parts resin to 300 parts Ferrosilicon by weight (Example II), the atomised grade of 70 Ferrosilicon containing 15 % Silicon being used The addition of 50 parts by weight of a liquid amidopolyamine to this composition gave a product which polymerised in 24 hours at 20 WC Exposure of the resultant 75 polymer in the ASTM B 117 Salt Spray showed no evidence of corrosion after 50 hours.

This work was carried out to determine the viability of Ferrosilicon as a replacement 80 for Iron powder in resin based compositions The following example takes this work one stage further.

In this example (Example III) the liquid resin from the reaction between 2 2 bis ( 4 85 hydroxyphenyl) propane and epichlorohydrin was blended with Atomised Ferrosilicon ( 15 % Silicon) in the ratio 100 parts liquid resin to 300 parts Ferrosilicon by weight To this composition 3 0 parts by weight of 90 coagulated silicon dioxide from the flame hydrolysis of Silicon Tetrachloride were added This addition gave the composition a degree of thixotropy and produced a more stable blend of resin and Ferrosilicon An 95 addition of 20 parts by weight of an acid metasilicate of Magnesium improved this thixotropy still further and produced a composition (Example III) with excellent storage stability The addition of 50 parts by 100 weight of a liquid amidopolyamine resin to the above material gave a composition which polymerised in 24 hours at 20 WC The resultant polymer was exposed in the ASTM B 117 Salt Spray, the BS 3900 Salt Spray, 105 the BS 3900 Humidity Cabinet and on natural exposure at Harrogate After 4,000 hours exposure in the above environments there was no sign of corrosion on any of the test pieces 110 Machining tests on solid rods of the polymerised composition given in Example III showed the material could be drilled, tapped and machined like conventional steel In addition the material was strongly 115 magnetic and had excellent abrasion resistance The following work compared the abrasion resistance of Examples I, II and III.

Mild steel panels coated with all three 120 examples given were tested on the Taber abrasion tester (manufactured by Taledyne Taber, New York) The Calibrade H 10 wheels were used in this test and a 500 gram loading was applied 125 After 500 cycles under the above conditions the following weight losses were recorded.

Composition in Example I 0 1350 grams Composition in Example II 0 0750 grams 130 1 600 612 Composition in Example III 0 0770 grams The above results clearly show the superior abrasion resistance of Compositions II and III based on 15 % Ferrosilicon.

Chemical resistance tests carried out on Compositions I and II in dilute acids, dilute alkalis and inorganic salt solutions ( 10 % solutions) over a period of 6 months showed that the Ferrosilicon based composition had considerably better chemical resistance and showed no signs of corrosion after 6 months immersion, whereas the composition (Example I) based on Iron powder had been attacked in every environment.

All the above examples I, II and III polymerised slowly at 20 WC and the object of the work carried out with these compositions was to examine the advantages of Ferrosilicon over Iron powder based compositions In the following example (Example IV) a composition with an improved rate of polymerisation was evaluated In this example the liquid resin from the reaction between 2 2 bis ( 4 hydroxyphenyl) propane and Epichlorohydrin was blended with spherical atomised 100 mesh Ferrosilicon ( 15 % Silicon) in the ratio 100 parts Resin to 300 parts Ferrosilicon 3 0 parts by weight of coagulated Silicon dioxide and 20 0 parts by weight of an acid metasilicate of Magnesium were added to produce a thixotropic composition.

The addition of 90 parts by weight of mercaptan terminated liquid polymer and 10 parts by weight of Tris 2-4-6 dimethylaminomethyl phenol gave a composition which polymerised rapidly at room temperature and which was relatively hard after 20 minutes reaction.

A comparison between this composition Example IV) and a composition where the 300 parts of 100 mesh Ferrosilicon were replaced weight for weight with Iron powder (Example V) gave the following results.

After 100 hours exposure in the ASTM B 117 Salt Spray the Ferrosilicon based composition (Example IV) was completely rust free whereas the Iron based composition (Example V) showed considerable rusting and corrosion.

A further composition (Example VI) with an improved rate of polymerisation was examined as follows The liquid resin from the reaction between 2 2 Bis ( 4 hydroxvphenyl) propane and epichlorohydrin was blended with Atomised Ferrosilicon ( 15 % Silicon) in the ratio 100 parts resin to 300 parts Ferrosilicon 3 0 parts coagulated Silicon dioxide and 20 0 parts of an acid metasilicate of Magnesium were added to the above blend to produce a thixotropic composition (Example VI) This composition was polymerised by the additon of 25 parts of a liquid activated aromatic polyamine The resultant polymer was hard after 1 hour at room temperature and on exposure in the ASTM B 117 Salt Spray showed no sign of corrosion after 500 hours exposure.

Storage tests on the unpolymerised com 70 position (Example VI) however showed that after prolonged storage at 20 WC this formulation tended to stiffen and eventually crystallise The following work was carried out in examining a composition which was com 75 pletely stable at 20 'C even after prolonged periods of storage.

The reaction product from 2 2 Bis ( 4 hydroxyphenyl) propane and epichlorohydrin was blended with 100 mesh atomised Fer 80 rosilicon ( 15 % Silicon) in the ratio 80 parts resin to 300 parts Ferrosilicon 20 parts of an epoxylated phenol formaldehyde resin were added to this composition followed by 3.0 parts coagulated Silicon dioxide and 85 20.0 parts of an acid metasilicate of Magnesium This composition (Example VII) showed excellent storage stability with no stiffening or crystallisation even after prolonged storage 90 Polymerisation of this composition with parts of a liquid activated aromatic polyamine produced a polymer which showed no sign of corrosion after 1,000 hours ASTM B 117 Salt Spray 95 Further examination of Ferrosilicon based compositions led to an investigation into the abrasion resistance of polymers containing Ferrosilicon in combination with abrasion resistant fillers In particular fillers 100 such as Quartz flour, Aluminium oxide and Silicon Carbide were examined in combination with 15 % Atomised Ferrosilicon This work indicated that combinations of Ferrosilicon and Silicon Carbide produced 105 polymers with outstanding abrasion resistance while still retaining many of the advantages of polymers based on Ferrosilicon alone.

In Example VIII the liquid resin from the 110 reaction product between 2 2 bis ( 4 hydroxyphenyl) propane and epichlorohydrin was blended with 100 mesh atomised Ferrosilicon in the ratio 100 parts resin to 250 parts Ferrosilicon by weight 50 parts by weight of 115 mesh Silicon Carbide were added to this blend followed by 3 0 parts coagulated Silicon Dioxide and 20 0 parts of an acid metasilicate of Magnesium.

The resulting composition was polymer 120 ised with 25 parts of a liquid activated aromatic amine to produce a polymer with outstanding abrasion resistance.

Tests carried out on the Taber Abrasion Tester using Calibrade H 10 Wheels and a 125 500 gm loading gave the following results.

Composition as given in Example III 0 0770 grams Composition as given in Example VIII 0.0160 grams 130 1 600 612 The above figures are expressed as weight of polymer removed after 500 cycles and clealy show the superior abrasion resistance of the polymer given in Example VIII This polymer still exhibited many of the advantages of earlier examples, in that the material was strongly magnetic and could be drilled and tapped like conventional metal The machining characteristics of this polymer were inferior to Examples II to VII however The presence of Silicon carbide producing excessive wear on any tool tips used in the machining process.

In addition to the above work on abrasion resistant fillers a wide range of adhesion promoters were evaluated in Ferrosilicon based compositions This work showed that monomeric organo-functional silicon compounds produced a marked improvement in the adhesion of Ferrosilicon based polymers to both metal and mineral substrates.

In Example IX the liquid resin from the reaction between 2 2 bis ( 4 hydroxyphenyl) propane and epichlorohydrin was blended with 100 mesh atomised Ferrosilicon in the ratio 100 parts resin to 300 parts Ferrosilicon 3 0 parts coagulated Silicon dioxide and 20 0 parts by weight of an acid metasilicate of Magnesium were added to the above blend followed by 1 O parts of gamma Glycidoxypropyltrimethoxysilane.

The above composition (Example IX) was polymerised using 25 01 parts of a liquid activated aromatic polyamine produced a polymer with outstanding adhesion to metal surfaces.

In adhesion tests carried out according to ASTM D 1002-53 T the polymerised composition given in Example IX was compared with the polymerised composition given in Example III Bonded steel specimens coated with both compositions give the following results at 20 WC.

Adhesion to steel of polymer from Example III 2,200 psi.

Adhesion to steel of polymer from Example IX 2,500 psi.

In addition to the above results the polymer containing the organo-functional silane (Example IX) gave improved adhesion results on oily and on wet steel substrates The following figures illustrate these improved results, again the tests were carried out according to ASTM D 1002-53 T.

The contaminated steel substrates were obtained by dipping the steel test pieces in mineral oil and water respectively at 20 WC and allowing the test piece to stand for 30 minutes prior to the application of the polymer under test.

Adhesion to oily steel of Polymer from Example III 1,140 psi Adhesion to oily steel of Polymer from Example IX 1,860 psi Adhesion to wet steel of Polymer from Example III 760 psi Adhesion to wet steel of Polymer from Example IX 1,280 psi The work outlined in Example I to IX has involved the evaluation of Atomised Fer 70 rosilicon in a liquid resin from the reaction between 2 2 bis ( 4 hydroxyphenyl) propane and epichlorohydrin In Examples X and XI the use of Ferrosilicon in alternative polymer compositions was investigated In Example 75 X 100 parts of a liquid branched polyalcohol with a hydroxyl content of 5 % were blended with 300 parts of 100 mesh atomised Ferrosilicon 3 0 parts coagulated silicon oxied and 200 parts of an acid metasilicate of 80 magnesium were added to the above blend followed by 10 0 parts of a crystalline aluminosilicate with a cavity diameter of 11.4 A This composition (Example X) was polymerised by the addition of 40 parts of 85 diphenyl methane 4-4 diiscocyanate The resulting polymer was exposed in the ASTM B 117 Salt Spray and showed no sign of corrosion after 500 hours exposure The formulation was strongly magnetic and could be 90 machined, tapped and drilled with ease.

Comparison between this comparison and a similar composition based on Iron powder showed almost identical machining properties The latter material showed consider 95 able corrosion in the ASTM B 117 Salt Spray after only 100 hours exposure however.

In Example XI an unsaturated polyester resin containing 35 % styrene by weight was 100 blended with 100 mesh atomised Ferrosilicon ( 15 % Silicon) in the ratio 100 parts resin to 300 parts Ferrosilicon by weight 3 0 parts coagulated silicon dioxide and 20 0 parts of an acid metalsilicate of magnesium 105 were added to this blend to produce a thixotropic composition (Example XI) The addition of 10 0 parts of a 50 % dispersion of Benzoyl Peroxide in dibutyl phthalate plasticiser gave rise to rapid polymerisation and 110 a hard polymer was produced within 20 minutes of the peroxide addition This polymer was exposed in the ASTM B 117 Salt Spray and showed no signs of corrosion after 500 hours exposure A similar compos 115 ition on Iron powder showed extensive corrosion in the same test after only 100 hours exposure.

The polymer from Example XI was strongly magnetic and could be machined, 120 drilled and tapped like conventional metal.

In addition the storage stability of this composition was considerably better than that of a similar composition based on Iron powder.

After 6 months storage at 20 C the Base 125 component was still in good condition whereas it is a known fact that unsaturated polyester resins blended with Iron powder have a limited storage life of 1-2 months.

This improved storage stability is obviously 130 1 600 612 due to the reduced reactivity and passivation of the Ferrosilicon powder after the atomisation process.

All the above work has been based on the atomised Ferrosilicon powder containing % Silicon and in the following examples the relative merits of 15 %, 45 %, and 75 % Silicon contents in Ferrosilicon are examined.

The liquid resin from the reaction between 2 2 bis ( 4 hydroxyphenyl) propane and epichlorohydrin was blended with an acid metasilicate of magnesium in the ratio parts resin to 20 parts metasilicate by weight 3 0 parts of coagulated silicon dioxide were added to the above blend to produce a semi thixotropic composition.

From this basic composition three polymers with varying silicon contents were produced:The addition of 300 parts of 15 % spherical Ferrosilicon and 25 parts by weight of activated aromatic polyamine produced a polymer (Example XII) with a low silicon content.

The addition of 300 parts of 45 % Atomised Ferrosilicon and 25 parts by weight of activated aromatic polyamine produced a polymer (Example XIII) with a medium silicon content.

The addition of 300 parts of 75 % Atomised Ferrosilicon and 25 parts by weight of activated aromatic polyamine produced a polymer (Example XIV) with a high silicon content.

Examinations of the above Polymers (Examples XII, XIII and XIV) in the ASTM B 117 Salt Spray showed no evidence of corrosion after 1,000 hours exposure.

The composition in Example XII ( 15 % Silicon) was strongly magnetic whereas Example XIII ( 45 % Silicon) was only weakly magnetic and Example XIV ( 75 % Silicon) showed no evidence of magnetism.

Furthermore the compositions given in Examples XIII and XIV were dry and difficult to mix, particularly Example XIV For a practical formulation the level of Ferrosilicon would have to be reduced.

The abrasion resistance of all three formulations was of a similar order and was consistently higher than the abrasion resistance of a composition based on Iron powder as in Example I.

A comparison between the relative merits of spherical and granular Ferrosilicon is given in the following examples.

The liquid resin from the reaction between 2 2 bis ( 4 hydroxyphenyl) propane and epichlorohydrin was mixed with 100 mesh atomised Ferrosilicon ( 15 % Silicon) in the ratio 100 parts Resin to 300 parts Ferrosilicon by weight 3 0 parts of coagulated Silicon dioxide and 200 parts of an acid metasilicate of magnesium were added to the above blend to produce a thixotropic composition (Example XV) The compositon was polymerised by the addition of 25 parts of a liquid activated aromatic amine.

This polymer was compared with a similar 70 composition where the spherical Ferrosilicon was replaced on a weight for weight basis with 100 mesh granular Ferrosilicon ( 15 % Silicon) Exposure of the two materials in the ASTM B 117 Salt Spray, the BS 75 3900 Salt Spray and the BS 3900 Humidity Cabinet for 1,000 hours showed no evidence of corrosion with either composition although very slight rust staining was observed with the granular Ferrosilicon 80 based composition.

Abrasion resistance tests and machiningtests gave identical results for both formulations.

From these results it can be seen that both 85 granular and spherical Ferrosilicon show considerable advantages over Iron powder in two component metal repair compositions Both alloys display outstanding corrosion and abrasion resistance and produce 90 compositions which can be drilled, tapped and machined like conventional metal.

The level of Silicon in the Ferrosilicon alloy can be varied considerably although optimum results are obtained with a com 95 position based on 15 % Silicon, 85 % Iron.

Claims (1)

1. WHAT WE CLAIM IS:-

   1 A method of repairing metal parts comprising replacing worn or damaged portions of metal in said parts with a composi 100 tion comprising a liquid polymerisable resin and a hardener for said resin, said composition also including a filler to impart metallic characteristics, said filler being ferrosilicon.

   2 A method according to claim 1 105 wherein the resin is an epoxy resin.

   3 A method according to claim 1 wherein the resin is a saturated polyester, a polyester polyol, an isocyanate-terminated prepolymer, a polyamine, a polyamide, a 110 polymercaptan, a silicone, an unsaturated polyester, an acrylate or a methacrylate.

   4 A method according to any of the preceding claims wherein the ferrosilicon is a granular or spherical powder or a blend of 115 both.

   A method according to any of the preceding claims wherein the silicon content of the ferrosilicon is from 10 to 80 parts by weight per 100 parts by weight ferrosilicon 120 6 A method according to claim 5 wherein the silicon content of the ferrosilicon is from 10 to 20 parts by weight per 100 parts by weight ferrosilicon.

   7 A method according to claim 5 125 wherein the silicon content of the ferrosilicon is about 15 parts by weight per 100 parts by weight ferrosilicon.

   8 A method according to any of the preceding claims wherein the terrosilicon is 130 1 600 612 parts by weight per 100 parts by weight of resin.

   9 A method according to any of the preceding claims wherein the composition also includes silicon carbide in an amount of from 40 to 60 parts by weight per 250 parts by weight ferrosilicon.

   A method according to any of the preceding claims wherein the composition also includes a silane as wetting agent, present in an amount of from 0 5 to 1 5 parts by weight per 100 parts by weight of resin.

   11 A method according to any of the preceding claims wherein said composition is obtained by mixing the two components of a two component pack comprising a first component including said liquid polymerisable resin and a second component including said hardener for said liquid polymerisable resin, one or both of said first and second components also including ferrosilicon.

   12 A two component pack comprising a first component including a liquid, present in an amount of from 250 to 350 polymerisable resin and a second compo 25 nent including a hardener for said resin, one or both of said first and second components also including ferrosilicon.

   13 A method according to claim 1 and substantially as herein described 30 14 A method according to claim 1 and substantially described in any of Examples II to VX.

   A two component pack according to claim 12 and substantially as described 35 herein.

   URQUHART-DYKES & LORD, Chartered Patent Agents, Agents for the Applicants, 11th Floor, Tower House, Merrion Way, Leeds, L 51 8 PB.

   and 11th Floor, St Martin's House, 140, Tottenham Court Road, London, W 1 P OJN.

   Printed for Her Majesty's Stationery Office by The Tweeddale Press Ltd, Berwick-upon-Tweed, 1981 Published at the Patent Office, 25 Southampton Buildings, London, WC 2 A l AY, from which copies may be obtained.