EP3089839A1

EP3089839A1 - Composite metal product

Info

Publication number: EP3089839A1
Application number: EP14876789.0A
Authority: EP
Inventors: Xinhu TANG; Kevin Francis Dolman
Original assignee: Weir Minerals Australia Ltd
Current assignee: Weir Minerals Australia Ltd
Priority date: 2013-12-30
Filing date: 2014-12-30
Publication date: 2016-11-09
Anticipated expiration: 2034-12-30
Also published as: AU2014374832B2; CA2934084C; CA2934084A1; CN105899311B; ZA201603623B; AU2014374832A1; BR112016015487A2; US20170022588A1; WO2015100472A1; EA033878B1; PE20160906A1; CL2016001685A1; BR112016015487B1; PL3089839T3; EA201691326A1; EP3089839A4; EP3089839B1; CN105899311A

Abstract

A centrifugally cast composite metal product having an axis of rotational symmetry and a mass of at least 5kg, comprises a host metal and insoluble solid refractory particles of & refractory material in a non-uniform distribution throughout the host metal. The particles have a density that is within 30% of the density of the host metal at its casting temperature.

Description

COMPOSITE METAL PRODUCT

e present disclosure elates to a method of ~ Hriii 1 ^r f ^ i*i ¾ "S t 4

finished product typically ranging in mass from 20-5,000 kg, having a host metal matrix, typically a ferrous metal matrix, and comprising outer surface layer, omi ally 1—20 m thick, of hard, insoluble refractory particles for enhanced wear resistance.

The p esen disclosure also relates to centrifugrally cast composite metal products,

In the context of the present disclosure, the term " ef ac o y particles''' is understood, to include particles of high melting point carbides and/or nitrides and/or borides of any one Of more than one of the nine transition metals titanium, zirconium, hafnium, vanadium, niobium, fe&nfcaluKi, chromium molybdenum and tungsten dispersed in tough host metal, which acts as binder phase. Each of these refractory particles is a particle of a refractory material". Typically, the host metal is a ferrous metal alloy. The host metal may also be nickel-based and.

cobalt-based superalloys .

In the context of^" the present disclosure, the term ^insoluble" is understood to mean that, for all intents and purposes, the refractory material is not soluble in the host metal at the casting temperatures, typically in a range 1200 -I60G°C for ferrous host metals. There ma be limited solubility. However, the refractory particles are essentially distinct from the host metal to the extent that there is negligibl partitioning of the elements in the refractory material particles to the host metal during the casting method and in the solidified product.

In a first as ct, embodiments a e disclosed, of a centri ug&lly cast composite etal product hav ng an axis of rotational symmetry and a mass of at least 5kg_f

typically at least 10 kg, and more typically at least 20k.g , a.nd costi sxsing a. x&et&l host: &χιό XnsoXubXe soX d distribution throughout the host metal, wherein the particles have a density that is within 30%, typically within 20%, of the density of the metal host at its casting temperature, h composite metal product comprises two distinct throughout the solidified material , naxsely a zone of insoluble solid particles of the refractory material and asi at least substantially refractory particle-free region of the host metal, with the refractory particles being essentially distinct f om the host metal to the x t that there is negligible partitioning of elements in the refractory material particles to the host metal at the casting temperature and in the solidified product.

The feature of the invention of solid particles of the refractory material that are insoluble in the host metal at the casting temperature and after solidification distinguishes the invention from proposals in the prior art, such as JPS632864, for the addition of ferroalloys (a) e~W_f (b) Fe~Mo and (c) Fe~Cr to a host ferrous alloy that forms respectively (a) tungsten carbide, (b

molybdenu carbide and (c) chromium carbide which are soluble to varying degrees in the host metal at the usual casting temperatures. As consequence, in these systems, the volume % of hard, insoluble refractory carbides in the microstruet r® is substantially reduced and the dissolved tungsten and/or molybdenum and/or chromium may adversely infl ence the physical and. chemical properties of the host metal at room temperature by an unknown amount, { .g.

reduced toughness and a different response to heat

ea men ) ,

In some embodiments, the refractory particles may have a density that is higher tha that of he host metal , in which case there will be a higher concentration of the r£¾ Λ †"f"* y y Λ Ύ'†" "ϊ ,^1 *s* s¾ r¾ β t'& i >~*~< y >s*s^■¾ F:¾ Λ ,-·> -p 4- Ή composite centrifugally cast metal product. a &¾a

have a density that is lower than that of the host metal., in which case there will be a higher concentration of the refractory particles towards an interior surface of the product .

In some embodiments , the non—uni orm dis ribution of refractory particles may comprise a first concentration of refractory particles in an exterior or interio surface layer of the product that is higher than a second,

concentration of refractory particles in another layer in the product.

In some embodiments , the first concentration of re actory ^ a t. l s m h ^ ror s rf c layer of the product may be at least 50 vol% , typically at least 60 vol%, typically at least 70 vol%, and more typically 50- 120 vol% higher than th nominal volume percentage of the refractory material in the product.

In some embodiments, the first concentration of product may be at least 10%, typically at least 20% , typically less than 40%, and more typically in a range of 10-40 vol%, of th® total voliame of th® exterior surface l yer .

In soma embodiments, the second concentration of refractory particles in the other layer of the product may be in a rang'© of 2-4.5 vol%, typically 2-3,5 vol! , o£ the total volume of the other laye .

In sonte ensbodi en s , the exterior or interior surface layer of the product may extend at least 5% _f typically at least 20%, xaor© typically a least 25% of the radial thickness of the product from the exterior or interior surface ,

In some embodiments , the exterior or interior surf ce layer of the product may extend less than 50% , typically less than 40%, more typically less than 30%, and store typically less than 20% of th® radial thickness of th® product from the exterior or interior surface.

In some embodiments , the exterior or interior surf ce layer of the product may extend at least 10 mm, typically least 20 nss&, typically less than 50 ΪΪΗΏ., typically 1—50 mm, and more typically 5-20 mm from the exterior or

In sΟΓ&Θ exnfoodiinents , the first conc@nt & ion of

or the product may be in a range of at least 5 vol% , typically at least 10 vol%, typically 5-90 vol%, and more typically 10™ 40 vol%, of the total volume of the particles.

Xn soiae embodiments , the ov all concentration of the

A. ¾SJ_*ΛfiS, LWAs J .UU.i L SB. 4-

^*vol%, typically at least 10 vol%_f and more typically in a range of 5~S0 vol% of the total volume of the product. In some embodiments, the overall concentration of the refractory particles in the product may be in a range of 5-40 vol% of the total volume of the product, In some embodiments , the overall concentration of the refractory particles in the product may be in a range of 5-20 vol% of the total VOI KS© of the product.

In some embodiment ^■, the refractory particles si y be carbides and/or borides and/or nitrides of one or more chemical mixture (as opposed to a physical mixture) of the c s lDilci s and o ^* I osricl&s

nieT» s . in o iie oras , m .n& cass oi carciues , uus refractory particles may be of the type described as

{Mi,M₂}C or (Mi_fM₂ M₃JC , where "M" is a transition metal. One example that is discussed further herein in

{t$b r i , ) C . The host metal may be any suitable host metal. Th host metal may be a ferrous alloy., such as a stainless steel or an austenitic manganese steel or a cast iron. The host metal may be a non-ferrous host metal , such as titanium or a titanium alloy,

In some embodiments, the host metal may be an alloy comp is g any on of the following alloys :

(a) Hadfield steel for use for example in cura ory crusher mantles

(b) 420C stainless steel for use for ex m l in shaft sleeves in slurry pumps; and

(c) high chromium white cast iron.

As used in some eisbodime , the Hadf 1¾ SS €£€_* £ΐ!3>^ comprise:

1.0 - 1.4 wt% C

0.0 - 1.0 wt% Si, - δ -

10 - 15 t% Mn,

0.0 - 3,0 wt% Mo,

0.0 - 5.0 t% Cr,

0.0 - 2.0 wt% Hi,

with the remainder being IPe and incidental impurities .

As used in soni© embodiments , the 420C stainless steel may cosaprise ;

0.3 - 0.5 wt% C,

0.5 - 1.5 wt-% Si ,

0.5 - 3.0 wt% M ,

0.0 - 0.5 wt% Mo,

10 - 14 t% Cr,

0.0 - 1.0 wt% Mi _f

wit the remainder being Fe and incidental impurities. s used in some em Gd Kien s , he h g c r aiuni white cast iron may comprise:

1.5 - 4.0 wt% C ,

0.0 - 1.5 wt% Si,

0.5 - 7.0 wt% Mn,

0,0 - 1.0 wt% Mo ,

15 - 35 wt% Cr,

0.0 - 1.0 t¾ n±,

with the remainder being Fe and incidental impurities .

The composite metal prod c may be any product that is adapted to be cen ifugally cast and eq i s high wear and high toughness properties . EKamples of such products include a gyratory crusher mantle for a primary, secondary or tertiary crusher, a slurry pump shaft sleeve, rollers for use in crushers {including large diameter rollers that are of the order of 1 m in diameter w t radial wall thicknesses in a range of 300—400 m ) , and other

components of crushers and pumps . In a second, aspect: , embodiments are disclosed in which the composite metal produc of the first aspect may be a gyratory crusher mantle for a primary, secondary or tertiary crusher.

In a third aspect, embodiments are disclosed, in which the com osi e me al product of the first aspect may be a slurry pump shaft sleeve . In a fourth aspect, embod en s are disclosed of a having an axis of rotational symmetry and a mass of at least 5kg , typically at least 10 kg, and more typically at

dispersion of insoluble solid refractory particles of a refractory e al, with the method comprising:

(a) forming a slurry comprising solid particles of

1 4" "" with the refractory particles comprising 5-50 vol% , typically 5-40 vol%, of the total volume of the slurry, with the refractory particle being insoluble at a casting temperature, and with the refractory particles having a density that is within 30%, typically within 20%, of the density of the metal host at the casting temperature; and (b) pouring the slurry into a mould for the

composite metal product and centrifugall casting the product in the mould and obtaining a non-uniform

distribution of insoluble solid refractory particles throughout the host metal .

In some embodiments, step (a) may comprise forming the refractory particles in situ in the molten host metal and dispersing the particles within a molten form of the host metal„

In some embodiments, step (a) may comprise adding re ractory particles to a molten orm of the host metal . In some embodiments, steps (a) and (fa) may be carried out under an inert environment, such as in an inert gas atmosphere ,

In some embodiments , step (b) may comprise preparing mould.

In some embodiments _f step (b) may comprise rotatxng the mould abou the axis to and/or u ina pouring the slurry into the mould to cause a concentration of refractory particles at or near an exterior surface or at or near an n-er o suiiace o XJTISS coiaposi ue mscai product that is higher than the concentration of particles elsewhe e in the produc ,

In some embodiments , ste (b) may comprise rotating the mould at a 10-120 G-Factor, where G-Factor is the centrifugal force acting on a rotating body divided by the gravitational force.

In some embodiments., step (b) may comprise rotating the mould at a peripheral speed of 2,5-25 m/s.

In some embodiments, step (b) may comprise rotating the mould for sufficient im to obtain the non-uniform d s ribution of solid oayfcicles h ouoiiesu h© host iss al

In some embodiments, step (b> may comprise rotating the mould until the host metal has solidified.

In som embodiments , step {b} may compri e pouring the slurry into the mould at a casting temperature in a range of 12Q0-2Q0G°C_i typically in a range of 1350-1650°C. In some embodimen s., the method may comprise

selecting the production parameters to form the slurry in step (a) that has a required fluidity for processing in step (b) .

The production parameters may comprise any one or solubility of the refractory materials , as described in International patent application PCT/AU2011/000092

(WO2011/0948OG) in the name of the present applicant. The incorporated herein by cross-reference. Density and belo . h© density of the refractory material of the

particles , com a d to the density of the host metal in the liquid state, is a parameter to consider ur g the method of the present disclosure to control the dispersion of refractory particles in the hot host m tal.

The nominal density o host ferrous liquid metal at 14Q0°C is 6,9 graiss/cc. When refractory particles in the form of tungsten carbide (WC) particles, with a density of 15.7 grams/cc at 25°C, are added to a hos ferrous metal to form the slurry, the WC particles will sink to the bottom of the slurry. When refractory particles in the forxa of titanium carbide (TiCj particles , th a density of 4.8 grams/cc at 1400°C, are added to the same host ferrous metal, the iC particles will float to the top of the slurry. Refractory particles in the form of niobium carbide (HbC) , with a density of 7.7 grams/cc at I4QG°C_f are fairly close to the density of the host ferrous liqu d metal at 6.9 grams/cc and are less prone to the above- described segregation in the liquid host ferrous metal than TiC or WC. TiC, with a density of 4,9 grams/cc at 25^riC,, is completely soluble in NbC , which has a density of ? .8 grams/cc at 25C . Therefore, refractory particles with densities in the range 4.9-7.8 grams/cc at 25°C can be obtained by selecting {Nb_f i)C particles with the required niobium and i aniu contents.

Tungsten carbide ( C) , with a density of 15.7

grams/cc at 25°C_r is mostly soluble in $3bC_f iC and

(¾tts,.Ti}C. Therefore _f refractory particles with densities in the range .8~15.7 grasss/cc at 25°C can he obtained by selecting {Hb^Ti _r ) C particles with the required niobium, titanium and tungsten contents . All refractory particles., described by the formula

(Mb , Ti _fW) C _f are insoluble in liquid ferrous host metals at casting em ures in he range 12Q0™i60G°C,

Hiobium carbide and titanium carbide have similar crystal structures and are isomorphou ,

It is evident from the abo e that selecting the required Mb: i ratio in a {3Sfb,,Ti)C chemical compound or th required Hb:Ti: ratio in a (Hb,Ti,W)C chemical compound can yield a refractory material with a required density within 20% of the density of the ferrous host m al .

The addition of refractory particles that are, for all intents and purposes, insoluble , (that is , having minimal solid solubility in a host liquid metal) , to produce a centrifugally cast casting of a composite metal product in accordance with the method of the present disclosure, produces a product that displays physical a d chemical properties that are very similar to the host metal with substantially improved wear resistance due to the presence of a controlled dispersion of a high ^■yolume % microstrue ure of the host metal.

For example, the solubility of a refractory material in the form of (Nb_fTi_fW)C in liquid host metals in the form of (a) liquid Hadfxeld steel and (h) liquid 420C stainless steel and fc) liqui igh chromium white cast iron at eleva ed temperatures is negligible (<0,3 wt% ) . The addition of (Hb_fTi,W)C with the required densities to these three host met l alloys, followed by centrifug&lly treatment procedure for each host metal produces

micros rue ures in the product comprising a dispersion of

]w? y

metals which are substantially free of niobium, titanium and t ngsten , that is _f he e is negligible partitioning of the transition metals in the refractory material slurry particles to the liquid host metal . Consequently, there is a negligible influence of the particulate refractory materials on the physical

properties (for example, melting point) and chemical propertie (for example, response to heat treatment) of the host metal .

In addition to the above , in particular the applicant has found that providing a composite metal product with a microstructure that includes particles of niobi m carbide and/or particles of a chemical (as opposed to a physical) mixture of two or more than two of niobium carbide, titanium carbide, and tungsten carbide dispersed in a matrix of a host metal considerably improves wear

resistance of the hard metal material without

oetrxx&enta y ax ectxng the contriDution that other alloying elements have on other properties of the

composite metal product, In addition, and as described above, in particular the applicant has found that it is possible to adjust the density of particles of a chemical mixture of two or more than two of niobium carbide, tit&niiam carbide and tungs en carbide to a sufficient extent in relation to the density of a host metal , wh ch forms matrix of he composite important finding in relation to centrifugally cast castings of the hard metal material .

In particular, by virtue of this finding, it is possible to produce centrifugally cast castings of the composite metal product with controlled non-uniform distributio , that is, seg ega ion, of the particles in parts of the castings, This is important for end-use applications for castings where it is desirable to have a concentration of high wear resistant particles near a

In a.ddLLti.on _f fciie applxc nfe les found. tJi fc foxni ng' castings of the composite mafeal product to inc

particles of niobium carbide and/or particles of

chemical mix ure of two or more than two of niobium carbide, titanium carbide and tungsten carbide in a range of 5-50 vol%, typically 5-40 wol% , more typically S-20 vol% of the total volum of the composite metal product, dispersed in a host metal , which orms a x of the corarsosi e lae al ∑>ro nct does not hav@ s. sig f can negative impact on corrosion resistance and toughness of ferrous material in the host metal. Hence, the present disclosure makes it possibl to achieve high wear

resistance of a composite metal product without a loss of

0 "i.€£.2 3.T 3. _* Accordingly, in a fifth aspect there is provided a method of centrifugall casting a composite metal product having an axis of rotational symmetry and a mass of at least Skg and comprising a host metal and a non-uniform d stribution of insoluble solid refractory particles of a refractory material, he method comprising adding (a niobium or (b) two or more than two of niobium and

titanium and tungsten to a melt containing a host metal in a form that produces solid refractory particles of niobium car&iu@ x; i3 . are insoxui s at a cas t-inc tsja sia Lure sns_/ o solid refractory particles of a chemical mixture of two or more than two of niobium carbide and titanium carbide and

a range of 5-50 vol%, typically 5-40 vol%_> more typically 5-20 vol%_f of the total volume of the product, and

centrifug lly casting the product in a raould and obtaining a non-uniform distribution of insoluble solid particle throughout the hos me al < he terms "a chemical mixture of niobium carbide and titanium carbide" and "niobium/titanium carbide'-' are hereinafter understood to foe synonyms. In addition, the term chemical mixture" is understood in

mean that the niobium carbides and the titanium carbides are not present as particles of si gl metal carbides in th mixture but are present as particles of

niobium/titanium carbides , (Mb, i) C ,

The terms ^¾a chemical mixture of niobium carbide and

"niobium/ itanium/ ungsten carbide" a

understood to be synonyms. In addition _r the term

^chemical mixture" is understood in this context to mean that the niobium carbides and the titanium carbides and the tungsten carbides are not present as particles of single metal carbides in the mixture but are present as particles of niobium/ itanium/ ungsten carbides,

(Hb,Ti, )C. Niobium carbide and titanium carbide and tungsten carbide each ha^e a Vickars hardness around 25 GPa, which is about 10 GPa above the hardness of chromium carbides (nominally 15 GPa) . Accordingly, composite metal products having a microstrueture containing 5-50 vol%_f typically 5~ 40 vol%_f more typicall 5-20 vol%_f of niobium carbide and/or n obium/ anium carbide and/or

niobium/titanium/tungsten carbide have excellent wear resistance properties . The applicant has recognised! that niobium carbides and titanium carbides and tungsten carbides and niobium/ itanium carbides and

niobium/titanium/tungsten carbides are substantially inert chemically with respect to other constituents in the composite metal product

product with the propertie for which they were selected. For ex le, c ium added to cast iron alloys still produces chromium carbides and provides corrosion

The niobium and the titanium and the tungs en may be added to a melt of the host metal to form the slurry in any suitable form_f bearing in mind the requirement of forming insoluble solid particles of niobium carbides and/or niobium/ i anium carbides and/or

niobium/titanium/ ungs en carbides in the composite metal product.

For sjtamole he metho sv ccsisDrise a dine? he niobium to the melt in the form of ferro-niobium., for example particles of" ferro-niobium. In this situation, the ferro-niobium dissolves in the melt and the resultant free niobium and carbon chemically combine to form

insoluble solid niobium carbides in the melt, The method may also comprise adding the niobium to the melt as elemental niobium. he method may also comprise adding the niobium and the titanium to the melt as ferro-niobium™titanium, he method may also comprise adding the niobium and the titanium and tungsten to the melt as ferro-niobiu - titan um-tungste ,

The method may also comprise adding the niobium to the melt in the orm of particles of i b um carbide .

The method may also comp s adding the i b an the titanium to the melt in the form of insoluble solid particles of niobium/titanium carbides

The method may also comprise adding the niobium and the titanium and the tungsten to the melt in the form of insoluble solid particles of niobium/titanium/tungsten

In each of these cases, the solidified metal alloy may be formed from a slurry of particles of niobium carbide and/or niobium/titanium/tungsten carbides

suspended, in the melt. Xf the weight fraction of these carbides in th melt slurry is too high, the flow

properties of the slurry may b© adversely affected with the result that unsound castings of the melt may be produced.

The insoluble solid particles of niobium/titanium carbides may be any suitable chemical mixture of a general ormula (Nb^ , J½) C .

The insoluble solid particles of

niobium/titanium/tungsten carbides may be any suitable chemical mixture of a general formula {Mb_x, i_y)Ws}C. By way of example, the niobium/titanium /tungste carbides may be {Hbe.25, TiQ.so,¾.25l C. The niobium and/or the titanium and/or the tungsten may be added to he melt to roduce insoluble solid particles of niobium carbide and/or niobium/titanium carbides and/or niobium/ itanium/tungsten carbides in a rang© of 12-33 t% niobium carbides or niobium/tita ium carb des or niobium/ itanium t ngs e carbides of the total weight of the cast product.

The niobium and/or the titanium and/or the tungsten particles of niobium carbide and/or niobium/titanium rang© of 12-25 wt% niobium carbides and niobium/titanium carbides and niobium/ itanium/tungs en carbide of the total weight of the cast composite metal product. he quantity of particles of niobium carbide and/or niobium/ itanium carbides and/or niobium/ itanium/ ungsten carbide i the micro-structure of the solidified hard metal ma may depend on the system. he applicant is concerned particularly with solid hard composite metal products that include host metals in the form of ferrous alloys , such as ferrous alloys

described as high chromium white cast irons, stainless steels, and austeni ic manga ese steels (such as Hadfield steels) . For ferrous alloys the quantity of insoluble solid particles of refractory material in the form of niobium carbide and/or niobium/ itanium carbides and/or niobium/titanium/tungsten carbides in the final composite metal product may be in a range of 5-50 vol^'% _f typically 5 40 vol%, more typically 5-20 vol-%^·, of the total volume of the cast composite metal product. - 1? ~ he particle size of niobium carbide and/or

niobium/titanium carbide and/or niobium/titanium/ ungsten carbide may be in a range of I - 150 pm in diameter.

The method m y comprise stirring the slurry with an inert gas or magnetic induction or any other suitable and/or niobium/titanium carbides and/or niobium/

ti anium/ ungs en carbides in the slurry.

The method may comprise adding¹ particles of niobi carbide and/or particles of niobium/titanium/tungsten carbides to the melt of^* the host ferrous metals under

ex ent to which niobium carbide and/or niobium/ itanium /tungsten carbide ox dize while being added to the melt. he method may comprise adding particles of ferro- niobium and/or ferro- itanium and/or ferro- ungsten and/or ferro-niofoiix - itanium-tungsten to the melt under inert conditions, such as an argon blanke , to reduce the extent to which niobiu and/or titanium and/or tungsten ox diz while being added to the melt.

In a situation ¾?h@re particles of niobium/titanium /tungsten carbides are required in the cast composite metal product, the method may comprise pre~melting ferro- i ferro™txtanxu er o— gs e ana/or ferro-niofoium-titanium- ungs en under inert conditions and forming a liquid phase that is a homogeneous chemical mixture of iron, niobium and titanium and tungsten and solidifying this chemical mixture. The chemical mixture can then be processed as required, for example by crushing to a required particle size , and hen added to the melt (containing carbon) under inert conditions. The iron, niobium and titanium and tungsten dissolve in the melt and chemically combine with carbon to form niobium/ itanium /tungsten carbides in the melt.

Other aspects , f atures , and advantages will become apparent from the following detailed description when taken in conjunction with the accompanying drawings, which are a part of this disclosure and which illustrate, 3by way of e m le, principles of inventions disclosed.

BRIEF DESCRIPTION OF THE DRAWINGS

Notwithstanding any other forms which may fall within the scope of the m t od and res l ant c m osi e metal product as set forth in the Sum ary, specific embodimen s of the method and resultant composite metal product will now be described by way of exam l and with reference to the accompanying Figures, of which;

Figure 1 is a diagram that illustrates a typical centrifugal casting method;

Figure 2 is a SE image of a section of on of he samples from centrifugally cast test cylinder "37863'' (AOS host metal + 5 vol !¾>C particles) produced during

experimental work in relation to the inventions- Figure 3 comprises cross-sections of optical images of samples from centrifugally cast test cylinders ^w37628", "37629", ^W3763G'% and ^¾37655" (AGS host metal + S vol% l&C particles) produced during experimental work in relation to the inven ion;

Figure 4 is a graph of hardness versus distance from in relation to Figure 3; Figure 5 comprises optical images of cross-sections of samples from centrif gally cast test cylinders ^¾3763I"_f "37632", "37633", and "37636" (AOS host metal + 12 vol% MbC particles) produced during experimental work in relation to the invention;

£ lyu e ¾ IS a y e&pil OX lia iriSSS VeiauS Cl S uaiiCSS i oiti outer surfaces to inner surfaces of the samples described in relation to Figure 5;

of samples from cent if gally cast test cylinders "37634" (AOS host metal + 1 vol% H C particles) produced during experintent&l work in relation to the invention;

Figure 8 is a graph of hardness versus distance from outer surfaces to inner surfaces of the samples described in relation to Fig re 7;

Figure 9 is an optical image of a cross-section of a Ssffls le of a centri ugally cast test cylinder A352 (C21 host metal + 10 vol% NbC particles) produced during experimental work in relation to the invention;

Figure 10 is an optical image of a cross-section of the outer layer of the cross-section of the sample shown in Figure 9 after etching the sampl ;

Figure 11 is an optical image of a cross-section of a sample of a centrifugally cast test cylinder A323 cylinder (A49 host metal + IS vol% HbC particles) ; and

Figure 12 is a graph o£ hardness versus distance f oxu outer surfaces to inner surfaces of sections of the sample described in relation to Figure 11. Figure 13 is a graph of the thickness of the MfoC particle-rich outer layer versus the nominal vol% of ¾bC in the total composition of centrifugaliy cast cylinders of AOS host metal + HfoC particles; and

Figure 14 is a graph o he vol% bC in the f¾sC particle—rich outer layer versus the nominal vol% of HbC in the total composition of centrifugaliy east cylinders of AOS host metal + ¾ C particles.

Figure 1 was sourced from the internet and

s in diagrammatic fo m the basic steps centrifugal casting method. hese c n fugal casting steps include forming a molten melt and. pouring the melt into a suitable mould and rotating the mould about a vertical axis (in the case of the arrangement shown in the Figure) at a required rate of rotation to form a cast product.

In al e n ve arrangements, such as the arrangement used to carry out the experimental work described below, the casting mould is positioned horizontally and the mould is rotated, about a horizontal axis .

In the contesst of the present disclosure, typically the molten melt comprises a slurry of hard, insoluble solid refractory particles in a host metal and the cast product is a composite metal product, typically rangin in mass from 5 kg to 5_fQ00 kg, having a ferrous metal matrix (the host metal) and comprises a non-uniform distribution of hard, insoluble refractory particles in the ferrous metal m ix, specifically an outer surface layer, nominally !~2Q mm thick, of hard, insoluble refractor particles that provide enhanced wear resistance in the surface layer . he actual centrifugal casting conditions may be selected in any given situation based on the required

ns f actual o c to i c s * casting conditions include, by wa of ex le, he rate of rotation of the mould and the rotation time and the cooling conditions and the conditions in which the casting

Refractory particle property requirements m y

Density greater than or less than the host f rrous metal .

H s n ^cc-ss of 3 _*

Diameter less than 500 microns , preferably less than 50 microns.

10-80 vol refractory particles present in the hard surf ce laye ,

* 5-50 vo.1%, typically 5-40 vol% , more typically 5-40 vol%, refractory particles in the composite metal product.

The composite metal products produced by the

centrifugal casting process of the indention include by way of exam le only the following products :

1. Slurry pump shaf sleeves

® Stainless steel cylinders

» Size: ranging from 25-400 Ksm diameter, 10 50 mm wall thickness and 2000 mm long.

Outer surface layer, 1-10 m thick,

containing a igh concentration of hard, insoluble he prior art comprises hard faced welding a

stainless steel cylinder to obtain approximately 1 mm thick tungsten carbide surface layer. Hard-faced layers then require grinding/machining to achieve a smooth finis .

Centifug&lly casting a slur y u shaft le e in accordance with the invention permits the manufacture of a cylinder approximately 2000 mm long with a required

sKioo h, ha d surface layer in one casting operation. In number of shaft sleeves which range in length from 60 to 300 am. 2 , Outer surface of gyratory crusher mantles he standard composition of gyratory c usher nian Xe is austenitic manganese steal (Hadfield steel) . The initial hardness of Hadfield steel is appro imately 200 Brinell (HB) and he su fa e laye of the steel work hardens to approximately 550 HB in service while the interior maintains a lower hardness and ex emely high toughness. The yield strength for Hadfield steel with a hardness of 200 HB is about 1/3 the tensile strength.

Severe plastic deformation can occur in service before work hardening to 550 HB occurs. As a result, crusher mantles wear rapidly and undergo excessive plastic

deformation in the early stages of operation. All previous attempts to improve the initial hardness and yield

strength of Hadfield steel have invariably resulted in unacceptable loss in toughness and a high risk of

catastrophic cracking in service.

CentrifugaXly casting a Hadfield steel crusher mantle i e with the present disclosure and forming an outer surface layer of insoluble solid refractory carbides in the casting, while maintaining the original Hadfield steel composition in the body of the casting, provides a more wear-resis ant material with minimal loss of

toughness .

3. White cast irons

Centrifugally casting high chromium white cast irons with refractory particles produces composite metal products having surface layers containing a high

concesi sa on of efracfeorv t3&3rfcic @s for wear

Centrifugally casting breaker bars hammer tips and ground en aging tools from high chromium whit© cast irons with refractory particles produces a surface layer

containing a high concentration of refractory particles for improved wear resistance .

In order to investigate the invention the applicant has carried out extensive experimental work in relation to particles of a particular refractory maternal., namely HbC particles, in different ferrous host metals.

Spec fically, the experimental wo k investigated the effects of vol% of MfoC particles and wall thickness and centrifugal forces on the ¾%C-rich zon in centrifugally cast products.

Xn the experimental work fourteen cylinders were centrifugally cast in a horizontally arranged centrifugal casting arrangement. The fourteen cylindrical shaft sleeves with different concentrations of NbC particles and a ferrous-based host m tal, as summarised below, were centrifugally cast and machined and then tested.

* Four A3G1 cylinders (AOS host metal -f 5 vol% $£bC particles of the total volume) ,

® Four A3G3 cylinders {AOS host metal - 12 vol% HbC particles of the total volume) .

* Four A30 cylinders (AOS host metal + 17 vol% $3foC particles of the total volusie) ,

* One Ά352 cylinder (C21 host metal + 10 vol% NbC particles of the total volume) .

« One A323 cylinder (A49 host metal + 15 vol% H c particles of the total volu e) .

AOS is a eutectic high Cr cast iron, C21 is a 420C stainless steel , and A43 is a hypoeutectie igh Cr cast iron. e nominal compositions of the AOS, C21, and A49 ferrous alloys are as follows, with the amounts of each element i wtl :

1. RESULTS AND DISCUSSION

c with different nominal chemical compositions intrifugally cast at ^■v rious rotational speeds

1.1. Centrifugal casting of four A301 cylinders (AOS host metal 4- 5 "vol% NbC particles)

Four cylinders containing 5 vol% MbC pa s n eutectic high Cr cast iron host metal were o u al cast at various rotational speeds or centri ugal forces . The casting temperature was in a range of 1400-150G^eC. The density difference between the HbC particles and the host metal at the casting temperature was approximately 12%. The cylinder dimensions and casting conditions are

T le 1 , Dimensions and casting conditions of cylinders containing 5 vol% HbC particles

laoh 4Q0mm cylinder was sectioned into three rings of roughly 280mm, 20mm and lOOmm in length. The 20mm~thick rings were used for inspection and metallurgical

1.1.1.Metallurgical Examination

Sairsples we e prepare from each 20mra--thick ring by cutting through the thickness at two locations roughly iSit&m t and forming cross^sections of t e rings _* Each c as stiade erp&ndi. n1 x o th¾ onfc and inner dec eased from outer surfac to the inner surface. The samples were mounted, ground and polished following stand r ts graphic oced¾-ies _f a d were then e ched with Acidified Ferric Chloride (AFC) for raatallographic exas&inatio , The microstructures of the samples were examined with a scanning electron microscope. Also, an optical ereomicroscope was used for macroscopic

examination of the samples.

Analysis of the samples from the cylinders

established that the casting m c ©s ruc ure in each instance comprised the AOS e tectic high Cr cast iron host metal and a non-imiform distribution of solid MfoC

particles throughout the host metal, Figure 2 is a SEM im ge of a section of one of the samples , Figure 2 shows the non-uniform distribution of HbC particles in the host metal , The Figure indicates that NfoC was undetectable in the host me al , More particularly , the fibC particles we e found to be insoluble in

easting temperature and in the cast cylinders . Figure 3 com ises optical m ges of cross-sections of samples from cylinders ^w3?628", "37629",, "37630", and "376SS".

Figure 3a shows that the cylinder "37628" had a HbC particl -rich outer layer of about 2mm

thicknes . Internally of the outer layer there are three layers numbered 2-4 in the Figure . There are boundaries between the layers. Each layer is about 3~5OH& thick. The layers 2-4 form an inner region having a lower

concentration of HbC particles than the outer layer.

Figur 3b shows tha th sample from cylinder "37629" had a similar layered (i.e. banded) structure, but with more layers than shown in Figure 3a. The high

concentration N C particle outer layer (identified by the numeral 1 in the Figure) is about 2mm thick with HbC

particles spread uniformly throughout the sampl . The outer layer 1 and. the innermost layer {identified by the numeral 6 in the Figure) are the most distinct, and the layers in between {i.e. layers 2-5 in the Figure) are very similar to one another in terms of appearance but are nevertheless distinct layers separated by boundaries. The microstruetures of layers 1 and 6 were found to be very different from each other as well as from the

microstruetures of layers 2-5, The microstructures of layers 2-5 were found to be quite similar to each other. Each layer 1-6 is about 3~4rnm thick. Cylinder ^«37630'" was cast a the highest rotation speed. Figure 3c shows that the sample had three layers , Compared to the samples of the other three cylinders, this casting had the lowest NbC particle concentration in the in e layers . e high rotation speed forced more MbC paixiciss t.o cxi¾ ou l ye , issui t-incj xri is uiicies<. high concentration HbC particle layer of all the castings . Cylinder ^B37€55" was cast at the same rotation speed as cylinder ^w37628"_? but was cast with a 5mm. thicker wall thickness . Figure 3d shows that the Bi C particle-rich layer in the sample from cylinder "37655" was b u 3.5mm th ck; grea er han tha is he saittOle fro cvlinde

"37628". This shows that even if rotation speeds are the s ta , a thicker wall results in a thicker MbC particle- rich zone.

The c particle ol™ fractions of (a) the MbC particle-rich outer layer and (b) the low concentration MbC particle inner layer were calculated from SEM images of various areas of th© layers at IGQx magnification. The values shown in Table 2 are the averages of multipl m asu emen s >

Table 2 , NbC particles in outer and inner layers

rora abl 2 , it is evident that the rotation speed during the casting had a effect on the MbC particle-ric ©titer layer of the cast cylinders . The sample for cylinder ^W3763G", which was cast at the highest speed, had the highest layer thickness and the highest volume fraction of the MbC particles, The sample for cylinder ^37629", which was cast with the second highest speed, came close in te ms of MbC voluitse faction , but he thickness o£ the layer was almost half that of the layer in sample "37630". Comparing the samples for cylinders "37628" and "37655" shows that even with the same rotatio speed, if the casting wall thickness is greater (i.e. more material) , then the HbC particle-~rich outer layer and its volume raction of MbC particles are greate as well .

In addition, all four castings had similar levels of MbC particles present in the non~concentrated MbC particle inner layers , collectively described as an ne region or each sample . Most of the MbC particles observ d in the small amount of spherical and dendritic MbC particles were also observed.

1,1.2, Hardness and ferrit© measurements Vickers hardness traverse tests with a load of 10kg were carried out on the polished surf ce of each sample . The measurements started at the outside diameter (OD) of each sample and then traversed through the thickness of the sample at list intervals to finish at the inside d am er (ID) of the sam le ,

Table 3 shows the average hardness and ferrite readings for each of th two regions . Traverse hardnes profiles are shown in Figure 4. Table 3. Hardness and ferrite measurements

Xt is eviden frost Table 3 a Figure 4 that the HbC particle-rich outer layer of each of the samples was considerably harder than the inner region of the sample and that the highest hardness values were typically at the outer surface of each sample and decreased uniformly to around 8 sam from the outer surface and r gained generally cons ant through, the remainder of the sassple . Xn

additio , the ferrite measurement results for the four castings showed a general trend of the KbC particle-rich outer layer ha ing highe ferrite measurements than the layers for&ti g the inner regions . The differences in ferrite content were mino , with the NbC particle-rich outer layers ranging from 13 to 16% while the inner regions ranged between 9 and 10% .

1,1.3, Summary

* All four of A301 centrifugal castings {A05 host metal 4* 5 vol% MbC particles) ex ib ted HbC segr ga n, resulting in outer layers of each sample having hig concentrations of ISibC particles .

* All four castings x ibi ed layers below the KbC particle-rich outer layer which were marginally different from each other. Each casting had a different number of layers .

_* The thickness and hardness of the WoC par icle- rich layers and the volume fractions of HbC particles in the outer layers of the cantrifugally cast cylinders depended on the different casting parameters, including casting rotation rate and wall thickness -

_* Samples for cylinders "37628" and "37655" were cast at the same rotation speeds but with different material mss, esul ing' in ions . he ^37655" sample h d a slightly thicker HbC particle—rich outer layer and it also contained a larger number of different banded layers through the thickness of the samples -

* The sample for cylinder "37629" was similar to the satsple for cylinder "37628", despite being cast at a gh r rotation speed. The faster rotation speed did not ax e i, rn© x.nicjiigss ox uie pa ucxs-ricii oute sysr but it did affect the volume fraction of NbC particles in the outer layer slightly._*

* The sample for cylinder "37630" sample was cast at the fastest rotation speed_f and this was reflected directly on several features. The sample had th thickest MbC particle-ric outer layer and the highest olum fraction of NbC particles in the outer layer.

Consequently, the hardness of the outer layer was the highest recorded for this group of cylinders.

* he ferrite measurement results for the four castings showed a general trend of the MbC particle-rich outer layer having higher ferrite measurements than the layers forming the inner regions . The differences in ferrite content were minor, with the HbC particle-rich outer layers ranging from 13 to 16% while the inner regions ranged between 9 and 10% . 1.2. Centri ugal casting of four Ά303 cylinders (Ά05 host metal + 12 vol% MbC particles)

Four cylinders were cast under the same conditions as the four cylinders described in section 1.1 above, with the same host metal (AOS) , but with a higher overall f¾sC volume £r&ction of 12% . The cylinder dimensions and rotational speeds are in Table . Table 4, Job codes nd dimension of cylinders containing

12vol% of HbC

Each 00 m cylinder was sectioned into h ee i gs of roughly 28Qxam, 20mm and 100mm in length. The 20mm- hick rings were used for inspection and metallurgical analysis . Samples were prepared and tested using the same

methodology described in section 1.1 a ov .

Fitxure 5 coiRi i es ostical images of saiaoles from cylinders ^w37631", "37632", "37633'% and "37636".

It is evident from IPigure 5

with the lower MbC particle volume fraction cylinders described in section 1.1 above _r the !¾C particles formed a non-uniform distribution in the host metal through the thickness of the castings, with the outer layers of the samples having higher concentrations of MbC particles.

Similarly, as was the case with the lower MbC

particle volume fraction cylinders described in section 1.1 above , SEM analysis established that KHbC was undetectable in the host metal. More particularly, the HbC particles were found to be insoluble in the host metal at the cas ing tem e ature and in the cast cylinders.

The HbC particle volume fractions of the HbC

particle-rich outer layers and the thicknesses of the outer layers we e calculated frost SEM ii&ssjes of various re s of the layers at lOOx magnification. The values shown in Table 5 are the averages of multiple

s&easurexnent .

Table 5 Thickness of outer layer and average vol%NbC particles

VIcke s & dn©ss t & e t:ests witit a, 1ο&,ό of 10kg

The measurements started at the outside diameter (OD) of each sample and then traversed through the thickness of diameter (ID) of the sample,

Table 6 shows the average hardness and ferrite eadi g's for each of the two egion . T a e © a dines profiles are shown in Figur 6„ Table 6. Hardness and Ferrite measurements

It is evident f om Tables 5 and 6 and Figures 5 and 6 that the same basic results were obtained with the highe voliime percentage of the A303 cylinde th the A301 cylinders described in section 1„ 1 above , 1,3. Centrifugal casting of four A304 cylinders (AOS host metal - 17 vol% BhC particles)

Four A3Q4 cylinders were centrifugally cast using the s&zae conditions as the A301 and Ά303 cylinders described in sections 1,1 and 1.2, respectively, above, wit the same AO5 host metal, but with a higher volume fraction of MbC particles. Samples were prepared and tested as described in sections 1,1 and 1,2 above, Only three cylinders were examin d {cylinder ^w37634" cast at 920rpm, cylinder ^,37635" cast at llOOrpm and cylinder ^M37636" cast a 1280 r m}„

Figure 7 comprises optical images of cross-sections of samples from cylinders ^37634" &ηά 37635"\

It is evident from Figure 7 that, as was the case with the lower particle volume fraction cylinders described in sections 1,1 an 1,2 above, the SbC particles formed a non-uniform distribution in the host metal through the thickness of the castings,, with the outer layers of the samples having higher concentrations of N C particles . The cross-sections show a N C particle-rich outer layer (or region) and a lower ¥3bC particle

concentration inner region (which may include multiple layers sepa at d by bou da ies} ,

In addition, as was the case with the lower KbC particle volume fraction cylinders described in sections 1.1 and 1.2 above, SE analysis established that MbC was undet ct ble in the hos metal. Mo e particularly, the WoC particles were found to be insoluble in the host metal at the casting temperature and in the cast cylinders .

The test work indicated that the thicknesses of the NbC particle-rich outer layers in the samples for

cylinders ^37634" _r "37635" and "37636" were 12mm, 13mm and lS-¾xs_f respectively.

The volume concentrations of the MbC particles in the outer layers of these samples were 28% for cylinder

w37634", 25% for cylinde ^37635" and 29% for cylinder "37636".

Table 7 shows the average hardness and ferrite readings for each of th inner and outer regions of the samples from cylinders ^37634" and"37635". Traverse hardness profiles a e shown in Figu 8.

Table 7. Hardness and Ferrite readings

Ferrite Reading

Sampie Region HV1G

{¾ magnetic)

Outer 664 12.7

37634

inner 546 10.9

Outer 661 11,7

37635

Inner 513 10.1 It is evident from Table 7 and Figures ? and 8 that the s&T&e basic results we e obtained with the higher volume percentage of the A304 cylinders as with the H3G1 and A303 cylinders described in sections 1>1 and 1.2 above ,

1.4. Centrifugal casting of an A352 cylinder (C21 host metal 4· 10 vol% MbC particles) One A352 cylinder was centrifugally cast froia a C21 host metal w th 10 vol% £¾bC particles . Saxaple we e prepared and tested as described above.

Figure 9 coniprises an optical ma e of a cross-* section of a sample of the A352 cylinder.

It is evident f ont Figure 9 that, as was the case with the other test cylinders described above, the C particles formed a non-uniform distribution through the thickness of the casting, with the outer layer of the sample having a higher concentration of MbC particle ,

In addition, as wa the case with the other test cylinders described above, SE analysis established that NbC was undetectable in the host metal . More

particularly, the MbC particles were found to be insoluble st cylinders. As shown in Figure 9, the MbC-rich layer is a 20s?sm thick layer, 50% of the total radial thickness of the sample. It was found that the sample contained about 25vol% of MbC particles , After etching, three sub-layers of the 20 issa thick

NbC particle-rich outer layer were identified, and are shown in Figure 10. Figure 10 shows that the e was directional solidification across the sub-layers during centrifugal casting, It has been found that the columnar structure made a significant contribution to the wear

i f the c s i _*

1,5. Centrifugal casting of an A323 cylinde (A49 host sietal H* 15 vol% MbC particles )

One 323 cylinder was centrifugally cast from a A49 host xnetal and 15 vol% MbC particles. Saiapl

1.5.1. Metallurgical Examination Figure 11 comprises an optical image of a cross- section of sample of the A323 cylinder. It is evident froni Figure 11 tha _/ as was the case with the other test cylinders described abov , he MbC particles forssetl a non— uniform distribution through the thickness of the casting, with the outer layer of the sample having a higher

concentration of HbC particles .

particularly, the NbC particles wer found to be insoluble st cylinders. As is ev de om Figure 11, the NbC particle-rich outer layer is a very distinct band along the entire outer edge of the circle. This was visible at both macroscopic and microscopic levels . The depth of the bC pa icle-riefa outer layer was found to be consistent along the circumference at about 7~ 8mm, i.e. approximately 25-30% of the radial thickness of the sample. The MbC volume fraction of this outer layer was also found to be consistent in the eKaitii ed areas at about 28-31 vol% o the total volume o the outer layer.

A t f om the HbC concentrations , the

micros ructures of the outer and the inner layers were found, to have other significant differences . The MbC particles in th MbC particle-rich outer layer wer mostly round without any sharp edges, while those in the inner layers had a. va e y of shapes , ranging fro round to pointy dendritic shapes . The ma ri structure of the MbC particle-rich outer layer and the other layers could be distinguished primarily by the presence/absence of

"Chinese script" type C particles structure in the austenite dendrites of the matrix, Thi type of HbC structure was found extensively in the inner layers, but it was almost non-existent in he C particle-rich outer characteristics of the MbC particle-rich outer layer and the inner layers .

Ά very unique microstructur was found at the

boundary of the ¾3 C particle-rich outer layer and the inner layers . The m crostructure was characterised by the NbC particles being predominantly cross-shaped

(dendritic) . Some particles in this region resei&bled a shape that was a mix e of round and dendritic .

Vickers hardness traverse tests with a load of 10kg were carried out on polished surfaces of two samples . The measurements started at the outermost edges of the samples and then traversed through the thickness of the castings at mm intervals to inish at the innermost edges _Λ Table 8 shows the average hardness and ferrite reading for the MbC particle-rich outer layer and the inner layers of each sample. The MbC particle-rich outer layer of each sample is described as the ^wouter region" in the Table and the inner layers of each sample are described as the "inner region" in the Tabl . Traverse hardness profiles are shown in Figure 12.

Table 8, Hardness and Ferrite measurements

S le R&fi¾ WlO

Qtrter 455 22.9

4719C G-A

Inner 357 21.2

Outer 526 19.1

4719C C-B

Inner 315S 17.6

The high MbC particle concentration of the bC particle— ich outer layer {the outer region) naturally resulted in a higher hardness than the inner region for each sasi le . The hardness results correlated with the volume fraction results, where a higher bC volume fraction of the 4719CC—B sam le gave a highe hardness result than the 419CC-A sample. There was no significant difference in ferr te content between the two regions of ith e£er¾nce to Pig^* T 12, fcle ha ine&s vers® highest a the very outer edge of the samples (1·®· the first test points for both tests) and the hardness at the boundary of the two regions was around 425 Vickers, The inner ^b lk) region maintained consistent hardness throughout most of its thickne s. 2. CONCLUSIONS

2,4. Functionally Graded Materials

st work suH¾marisad above, host metals (AOS, A49 and C21) with a range of volume percentages of KbC particles wer centrifiscally cast and. examined. The results are suKKsa isad and presented in Table 9.

Table 9. Summary of centrifugally cast ¾.300-family alloys

The vol m fraction of refractory particles in the bC particle-rich outer layers of the castings were up to 31% in "volume of the otiter layer. In addition, high rotation speeds increased the HbC vol%, but the effects were typically v ry small . In the inner region of each casting, the volume percentage of MbC particles varied in the ang© £rom 2-6 , The relationship between thickness of the HbC

particle-rich outer layer and the overall vol% of HbC in the product compositions and the relationship between the vol% of NbC in the NbC particle-rich outer layer and the overall vol% NbC in the product compositions were analysed and the results are presented n F gures 13 a d 14 , respectively »

As can be seen f o the Figures :

(a) the thickness of the 1¾>C— ich outer layer of each centrifiugally cast cylinder was found to be directly dependent on the nominal bulk WsC content in the produc composition (see Figure 13) and

(h) the final HbC content in the HbC particle-rich outer layer of each centrifugally cast cylinder was found be dependent on the nominal bulk NbC content in the off at a maximum content of around 28-30% in the outer layer for the particular A05 host metal and being 50-120 vol% higher than the nominal volume percentage of the refractory material in the whole product across the nominal ¾¾C vol% range covered by Figure 1 ,

It was also found that the thickness of and th MbC particle concentration in the MbC particle-rich outer layer in each of the centr fugally cast cylinders was independent of the casting G-Factor in a range of 50-102.

Xn fo e om d sc i i o pref rred

embodiments , specific terminology has been resorted to for the sake of clarity. However, the invention is not intended to be limited to the specific terms so selected, and it is to be understood that each specific term

includes all technical equivalents which operate in a similar manner to accomplish a similar technical purpose. Terms such as "front" and "rear", "inner" and "outer", "above" _f "below", "upper" and "lower" and the like are used as words of convenience to provide reference points and are not to be construed as limiting terras.. The reference in this specification to any prior publication (or information derived from it) , or to any siaCtsr uicn is Kiiowii, is iiOx; , anc* siio i not, lae taiieii as, an acknowledgement or admission or any for® of suggestion that prior publicatio (or information derived from it) or known matter forms part of the common general knowledge in the field of endeavour to wh ch this s¾ecif cation

In this specification, he word ^¾comprising" is to he understood in its "o e " sense, that is, in the sense of ^including" , and thus not l mi ed to its ^¾>closed" se se, that is the sense of ^consisting only of". A

corresponding meaning is to be attributed to the

corresponding words ^>Acomprise", "comprised" and

"comprises" where they appear.

In addition, the foregoing describes only som

embodime s of the inventio (s) , and alterations,

*'i 3if*tr¾ ?w 5a y- « ;aγ"> " is ¾¾2a thereto without departing from the scope and spirit of the disclosed embodiments, the embodiments being illustrative and not restrictiv .

Furthermore, inventio (s) have been described in connection with what are presently considered to be the most practical and preferred ei¾bodiments , it is to be understood that the invention is not to be limited to the disclosed embodime s, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the inventio (s) , Also, the various embodiments described above may be implemented in conjunctio with other embodiments, e.g., aspects of one embodiment may foe combined with aspects of another embodiment to realize ye other embodiments.

Further, each independent feature or component of any given assembly may constitute an additional embodiment.

By wa of exampl , wh l the embodiments o£ the s eel (such as a stainless steel or an austenitic

m nganese steel) as the host m al, the inv ntion is riot limi ed to this type of host metal and ex end to any suitable host isetal. By wa of ex m le, the host metal may contain wherein the host metal contain any one or more of the transition me al elements Ti_r C , Er, Hf , V, Nb,

By ay of fur e exam le _r whilst e m odime s of the ven ion described above ocus on MbC as the material insoluble solid particles of ref actory m ri l ,< the invention also extends to other refractory materials.

By way of further example, whilst the embodiments of the invention described b e focus on NbC particles which ha e a density that is higher than that of the host metal, whereby there are higher concentrations of the refractory products, the invention also extends to embodiments in which the refractory particles have a density that is lower than that of the host metal, whereby there are higher concentrations of the refractory particles towards an interior surface of the composite metal product.

By way of further example, whilst the experimental work described above was carried out on centrifugally cast cylinders , it can readily be appreciated that the

invention is not limited to this particular shape casting and extends to any shape product that can be centrifugally cast.

Claims

CLAI S

1. A centri ugally cast composite metal product having an axis of rotational symmetry and a mass of at least 20kg and comprising a metal host and insoluble solid particles of a ref actory material in a non-uniform distribution throughout he host stetal _f whe ein the particles have a density that is within 20% of the density of the metal host at its casting temperature .

2. The composite e al produc defined in claim , wherein the non-uniform distribution of refractory

particles comprises a first concentration of particles in an exterior or interior surface layer of the product that is higher than a second concentration of particles in another layer in h produc ,

3. he composite metal product defined i claim 2,.

wherein the first concentration of refractory particles in the exterior surface laye of the product is in a range of 10-40 vol% of the total volume of the exterior

layer .

4. The composite metal product defined in claim 2 or claim 3 , wherein the second concentration of ref actory particles in the other layer of the product is in a range of 2-4.5 vol% of the total volume of the other layer.

5. The composite metal product defined in any one of claims 2 to , wherein the first concentration of

refractory particles in the exterior surface layer of the product is 50-120 vol% higher than the nominal volume percentage of the refractory material in the product,

6. The composite metal product defined in any one of layer of the product extends less than 50% of the radial thickness of the product from the exterior or interior surface of the product.

7. he composite metal product defined in any one of

5 claims 2 to 6 , wherein the exterior or interior surface layer of the product extends 1~50 mm from the exterior or interior sur ace of the product .

8. he cosiposite metal product defined in any one ofϋ claii&s 2 to I_f wherein the first concentration of

refractory particles in the exterior surface layer of the product is in a rang© of 5-9Q vol% of the total volume of the particles. 5 9, The composite metal product defined in any one of the receding claiias , wherein the overall concentration of refractory particles in th product is in a rancje of 5-50 vol% , typically 5-40 vol%, of the total volume of the produc .

0

10. The composite metal product defined in any one of the preceding claiias having mass of at least 50kg,

11, The composite metal product defined in any one of the 5 preceding claims having a mass of at least 75kg. composite metal product defined in any one of the density that is within 15% of the density of the metal0 host at its casting tempera ure,

13. The composite metal product defined in any one of the preceding claims, wherein the refractory particles are carbides and/or borxdes and/or

5 than one transition metal where the particles are a

chemical mixture (as opposed to a physical mixture) of the carbides and/or borides and/or tron metals .

14. The composite metal product defined in any one of the preceding claims, wherein the host metal is a ferrous alloy, such

15. The composite metal product defined in claim 14,

¾ e @i he host st&fcsl is an allov ccsitirs is ns anv one of the following alloys :

(a) Hadfield steel, for use for example in gyratory crusher mantles;

b) 420c stainless steel, for use £o∑ exam le in shaft sleeves in slurry pumps; and

(c) high chromium white cast iron,

16. he composite metal product defined in claim 14, wherein the host metal is Hadfield steel comprising:

1.0 ~ 1.4 wt% C

0.0 - 1,0 wt% Si,

10 - 15 ¾?t% Mn,

0.0 - 3,0 ¾?t% Mo,

0.0 - 5.0 t% Cr,

0.0 - 2.0 wt% Ni,

with the remainder being Fe and incidental impurities.

17. he composite metal product def ned in claim 14 , comprisi :

0.3 - 0.5 t% C,

0,5 - 1,5 wt% Si ,

0,5 - 3.0 wt% Mn ,

0.0 - 0,5 wt% Mo,

10 - 14 wt% Cr,

0.0 - 1.0 wt% Ni,

with the remainder being Fe and incidental impurities.

18. The composite metal product defined in claim 14, wherein the host metal is a high chromium white cast iron comprising:

1.5 - 4.0 wt% C,

0.0 - 1.5 wt% Si,

0.5 ~ 7.0 t% Mn,

0.0 - 1.0 t% Mo,

15 - 35 wt% Cr,

0.0 - 1,0 wt% Hi,

IS. The composite metal product defined in ny one of

1—14, wherein the host metal a non-ferrous metal.

20. The composite metal product def ned in any one of the preceding claims comprising a gyratory crusher mantle for a primary, secondary or tertiary crusher. 21. The composite metal product defined in any one of claims 1 to 19 comprising a slurry pump shaft sleeve .

22, A centrifugally cast composite metal product having an axis of rotational symmetry and a mass of at least 20kg and comprising a metal host and insoluble solid particles of a refractory material in a non-uniform distribution throughout he host metal , wherein the particles have a densi v that is wi hin 30% of he densi v of he i¾@ al host at its casting temperature.

23. A centrifugally eas composite metal product having an axis of rotational symmetry and a mass of at least 5kg and comprising a metal host and insoluble solid particles of a refractory material in a non-uniform distribution throughout the host metal, wherein the particles h ve a density that is within 20% of the density of the metal host at its casting temperatur ,

24. A method of centrifugally casting a composite metal product having an assis of rotational symmetry and. a mass of at least 20kg and comprising a host metal and a non~ 5 uniform dispersion of insoluble solid refractory particles of a ref actor material , the method comprising :

(a) formxng a slurry com ising' solid refractory particles dispersed in a liquid host metal., with the refractory particles comprising 5-50 vol% of the totalϋ vo ux&e of the slu y, with the ef ac o y particles being insoluble at a casting temperature,, and with the

refractory particles having a density that is within 20% of the density of the me al host at the casting

fessffi eira sTs ¹ and

5 (b) pouring the slurry into a mould for the product and centrifugally casting the product in the mould and obtaining ¾ non~uniforxtt distribution of ins ub e solid paixiciss x-nro ixou x-ne xios ex,a . 0 25. The method of centrifugally casting a composite metal product as defined in claim 24, wherein steps (a) and (fo) are carried out under an inert environment,

26. The method of centrifugally casting a composite metal 5 product as defined in claim 24 or claim 25, comprises

preparing the mould by forming an inert environment within the mould.

27. The method of centrif gally casting a composite metal0 product as defined in any one of claims 24 to 26, wherein step (b) comprises rotating the mould about the axis subse<uent to and/or during pouring the slurry into the mould to cause a concentration of refractor particles at or near an exterior surface or at or near an interior

5 surface of the product that is higher than the

concentration of particles elsewhere in the product.

28. he method of cen rifugally casting a composite metal produc as defined in any one of cl s 24 to 27, whe ein step ( ) comprises rotating the mould at a 10-120 G- Factor ,

29, he method of centrifugally casting a composite metal produc as defined in ny one of claims 24 to 28 , w erein s e (h) comprises rotating the mo¾ld at a peripheral speed of 2.5-25 meters/ second.

30 The method of centrifugally casting composite metal product as defined in claim any one of claims 24 to 29, wherein step (b) comprises rotating the mould until the host me

31. The method of centrifugally casting a composite metal product as defined in any one of claims 24 to 30, w erein step (b) comprises rotating the xitould for sufficient time to obtain the non-uniform distribution of solid particles throughout the host me al.

32 < The method of centrifugally casting composite metal product as defined in any one of claims 24 to 31 , wherein step fb) comprises pouring the slurr into the mould at a casting temperature in a range of 1200-1650°C_f typically in a range of 13S0-1550C, method of centrifugally casting a composite metal product as defined in any one of claims 24 to 32, wherein the composite metal product has a mass of at least 50kg.

34, The method of centrifugally casting a composite metal product as defined in any one of claims 24 to 33, wherein the composite metal product has a mass of at least 75kg.

35. The method of centrifugally casting composite metal product as defined in any one of claims 24 to 34, wherein the refractory particles have a density that is within 15% of the density of the metal host at its casting

temperature .

36. ft. method of centrifugally casting a composite metal product having an axis of rotational symmetry and a mass uniform dispersion of insoluble solid refractory particles of a refractory material, the method comprising:

(a) forniing a slurry comprising solid refractory particles dispersed in a licpxid hos K&etal, with the refractory particles comprising 5-50 vol% of the total olume of the slurry, with the refractory particles being insoluble at a casting em e a re _f and with the

refractory particles having a density that is within 20% of the density of the metal host at the casting

temperature; and

~> ou n uie sxu ry iiuo a G ci ΙΟΓ Ϊ.Ω« oo-wci; and centrifugally casting the product in the mould and obtaining a non-uniform distribution of insoluble solid particles throughout the host metal .

37. A method of ©sntrifugally casting a composite metal product having an axis of rotational symmetry and a mass of at least 5kg and comprising a host metal and a nonuniform dispersion of insoluble solid refractory particles of a refractory material, the method comprising:

(a) formin a slurry comp isi g solid refractory particles dispersed in a liquid host metal, with the refractory particles comprising 5-50 v©l% of th total volume of the slurry,

insoluble at a casting temperature, and with the

refractory particles having a density that is within 20% o£ the density of the metal host at the casting

temperature ; and

(b) pouring the slurry into a mould for the product and centr f gally casting the product in the mould and obtaining a non-uniform distribution of insoluble solid particles throughout the hos metal,

38 , A method of centrifugally casting a coinposite metal product having an axis of rotational symmet y and a mass of at lea 5kg and. co&tprisxng a host me al and. a n©n~uniforsft distribution of insoluble solid particles of a refractory material., the method comprising adding (a) niobium or (b) two or more than two of niobium and

titanium nd tungsten to a melt containing a host metal in a form that p oduces solid refractory particles of ob m carbide that are insoluble at a casting temperature and/or solid refractory particles of a chemical mixture of two or snore than two of niobiws carbide and titanium carbide and tungsten carbide that are insoluble at a casting

enspe tu © , with he solid refractory particles being in a range of 5-50 vol% of the total volume of the product, in a mould and obtaining a non-uniform distribution of insoluble solid refractory particles throughout the host metal.