DE10157079C5 - Matrix powder for the production of bodies or components for wear protection applications and a component produced therefrom - Google Patents

Abstract

A matrix powder for the production of components for wear protection applications, which consists of hard material in powder form and optionally a metallic powder, characterized in that a part of the hard material is in the form of spheroidal hard material particles, and part of the hard material is in the form of broken carbides, wherein between 30 and 60 wt .-% of the hard materials in the particle size range of 106 to 250 microns and 40 to 70 wt .-% in the particle size range of -106 microns.

Description

The invention relates to matrix powder for the production of bodies or components for wear protection applications as well as a component produced therefrom.

Matrix powders are processed in the prior art using an infiltrant to wear protection components, which are used primarily in the field of Erdölexploration.

State of the art

A special field of application for matrix powder is the production of diamond core bits for oil exploration. The relevant prior art results to the knowledge of the applicant from the US 5,733,664 , of the US 5,733,649 and the US 5,589,268 ,

In all three mentioned patents, broken cermets, mainly based on tungsten carbide with cobalt as the binding metal, as well as monocrystalline tungsten carbide (WC) and tungsten melt carbide, a eutectic mixture of WC and W2C, are sintered for the compositions of the matrix powders with respect to the hard materials.

In the US 5,733,664 in addition to sintered broken cermets on the basis of WC with cobalt as binding metal also sintered broken cermets on the basis WC with nickel are described as metallic binder.

The grain sizes of the hard materials used are according to all three patents in the size range of 45 to 180 microns or in the size range of 400 to 120 mesh, mixtures of different grain size fractions are called, however, in their entirety always in the range of 45 to 180 microns or from 400 to 120 mesh lie. The matrix powders listed in the patents may contain either a hard material component alone or else mixtures of different hard materials.

The US 5,733,664 and US 5,589,268 In addition to the actual matrix powders, they also include the infiltration materials. These are alloys of the composition Cu-Ni-Zn and Cu-Mn-Ni-Zn, in each case also with additions of Mn, B and Si.

In addition to the use of matrix powders for the production of diamond core bits describe the FR 2 667 804 A1 and the associated DE 691 00 258 T2 a method for producing abrasion resistant surfaces in which the abrasion resistant surface is formed by a composite material based on tungsten carbide powder bound in a solder alloy. The tungsten carbide powder used in this case consists of tungsten-melted carbide (WC-W2C), with the majority of the grains having a spherical shape and a diameter of more than 0.5 mm.

The according to the US 5,733,664 , of the US 5,733,649 and the US 5,589,268 For the production of diamond core bits used different matched grain size ranges of the individual hard materials should give the infiltration later produced from it in addition to a good abrasion resistance and a good erosion resistance. In practice, however, it has been shown that the hard materials used, if the surrounding matrix is eroded by erosion, provide a good point of attack for the wear-acting material.

In addition, these hard particles probably have a very high hardness, but are also very brittle in nature. The associated reduced impact resistance in turn facilitates the breaking, in particular of corners and edges of blocky grains of these materials. In addition, apart from the notch effect caused by the angular morphology of such hard materials, a further notch effect occurs on the surrounding matrix during the breaking of the hard materials, which can cause additional cracking in the surrounding matrix material. These crack inducements or cracks have a negative effect on the fatigue strength of the infiltrated component.

From the US 5,089,182 The applicant is a method for producing spherical tungsten carbide bodies with sizes between 40 microns and 2000 microns known.

task

It is an object of the invention to provide a matrix powder and a wear-resistant component produced therefrom, wherein an increased erosion resistance on the one hand and good processability of the matrix powder on the other hand is given.

This object is achieved by a matrix powder according to claim 1 and a component produced therewith according to claim 17. Dependent claims relate to advantageous embodiments of the invention.

The invention is based on the recognition that with regard to the wear resistance of the infiltrated components in the abovementioned compositions for matrix powder, the grain shapes of the hard materials used have a disadvantageous effect. Their blocky and angular morphology provides a good point of application for the wear-inducing material.

The disadvantages in the wear behavior of previous infiltration components can be significantly improved by the use of spheroidal hard materials, since spheroidal particles, insofar as they are in the same particle size range as the abrasively or erosively acting wear material, offer this a significantly lower attack surface.

In addition, spheroidal hard materials do not exert a notch effect in the surrounding matrix, which considerably improves the fatigue strength of infiltrated components. If spheroidal hard materials in the form of a densely sintered composite of metal carbides and a metallic binder are formed, then the impact strength of such hard particles compared to pure carbides can be improved, whereby the mentioned additional notch effect when breaking the particles can be reduced, which in turn results in an improved fatigue strength the infiltration body results.

The invention therefore relates to matrix powders which contain spheroidal hard materials in grain sizes which lie in the same order of magnitude as the attacking wear particles and thus improve the mechanical properties of the infiltrated components produced from them.

On the one hand, such hard materials can be spheroidal carbides, as they are known in US 5,089,182 the applicant are described. Similarly, dense sintered spherical powder with closed porosity or pore-free densely sintered powder come into question. Alternatively, it is also possible for the spheroidal hard materials to be in the form of sintered pellets of the type conventionally produced by various manufacturers, such as Kennametal Inc., Latrobe, Reed Tool Company, Houston and, among others, Applicants.

A matrix powder according to the invention for the production of components for wear protection purposes, which contains hard material present in powder form, is characterized in that a part of the hard material in the form of spheroidal hard material particles having a particle size of less than 500 microns. The particle size of the spheroidal hard materials is particularly preferably between 20 and 250 μm.

The above-mentioned advantageous properties of the matrix powder already arise when at least 5% by weight of the matrix powder is formed by spheroidal hard material particles. However, it is preferred that at least 30 wt .-% of the matrix powder are formed from spheroidal hard material particles, more preferably it is even more than 50 wt .-%.

In order to allow an infiltration of the matrix powder in a production of a component to be protected against wear, the invention provides that the matrix powder contains a further component which acts as a spacer, so that the spheroidal hard material particles are not stored too tightly, especially in the case of small particle sizes. For this purpose, the matrix powder contains blocky hard materials in the form of broken carbides. The grain size of these broken carbides is preferably between 3 and 250 microns. Examples of the usable blocky hard materials and the spheroidal hard materials are given in the embodiments.

Examples of the usable metallic powders are given in the embodiments.

According to a development of the invention, the matrix powder may also contain a metallic powder. The grain size of a metallic powder used is preferably between 20 and 150 microns.

The spheroidal sintered material which is suitable for the spheroidal hard material is a new development of the applicant, which is described in US Pat DE 101 30 860 A1 is described. The following, exemplary method for producing the sintered material is taken from the cited German patent application of the applicant.

An exemplary embodiment of a method for producing the sintered product is explained below:
As a powder starting material having a porous internal structure, the product already on the market of the applicant WOKA 9406 Co is used, which consists of 94 wt .-% WC and 6 wt .-% Co and which is an agglomerated sintered material , The selected powder starting material, which has a particle size range of 5 to 200 microns, wherein each 10 wt .-% may have a larger or smaller grain size than the upper grain or the lower grain is pre-fractionated by sieving. The pre-fraction is in the particle size range of 75 to 125 microns.

The agglomerate particles of the selected powder starting material are introduced into graphite boats, which are adjusted in a so-called sintered HIP furnace. It follows the sintering process step, at a temperature of about 1430 ° C and an argon gas pressure of 40 bar, the process time is 20 minutes.

Within the sintering step, the volume of the particles of the selected powder starting material is reduced by about 20%, so that densely sintered, agglomerated particles are present.

In the sintered HIP furnace, the sintered material is cooled. After carrying out the process, material bridges between the individual particles of the sintered material are present to a small extent. Therefore, a grinding of the sintered product for breaking up the material bridges takes place.

Subsequent to the step of grinding, a final cut is made to the finished sintered material having a grain size range of 63 to 106 μm. The final screening is only required if a different particle size distribution is desired than that which results after the grinding step.

The finished sintered material has a homogeneous distribution of the tungsten carbide and the cobalt, has a spheroidal outer shape due to the application of gas pressure, and is substantially free of pores.

• a) Bereitstellen eines im wesentlichen sphäroidischen Pulver-Ausgangsmaterials mit teilweise poröser innerer Struktur, das eine mittlere Korngröße hat, die im wesentlichen um die Größe des Porenanteils größer ist als die vorgegebene mittlere Korngröße der sphäroidischen Sinterpartikel und 80–90 Gew.-% sinterbaren Hartstoff einer Korngröße zwischen 0,6 und 5 μm und 3 bis 20 Gew.-% metallischen Binder einer Korngröße von 0,6 bis 5 μm enthält,
• b) Einbringen des Pulver-Ausgangsmaterials in einen Ofen,
• c) Sintern des Pulver-Ausgangsmaterials zunächst unter Beaufschlagung des Pulver-Ausgangsmaterials mit Wärme einer Temperatur, bei der das Material des metallischen Binders einen teigigen Zustand einnimmt, und dann unter Beaufschlagung mit einem Gasdruck, bei dem die Korngröße der einzelnen Partikel des Pulver-Ausgangsmaterials infolge der Verminderung des Porengehaltes des Ausgangsmaterials auf die vorgegebene mittlere Korngrößenverteilung der sphäroidischen Sinterpartikel vermindert wird, und
• d) Abkühlen der sphäroidischen Sinterpartikel und Entnehmen der sphäroidischen Sinterpartikel aus dem Ofen.

The above example is an embodiment of a method for producing sintered material from spheroidal sintered particles of predetermined average grain size in the range between 20 and 180 μm, which have a predominantly closed porosity or are free of pores, with the successive steps:

• a) providing a substantially spherical powder starting material having a partially porous internal structure, which has a mean grain size, which is greater by the size of the pore portion is substantially greater than the predetermined mean grain size of the spheroidal sintered particles and 80-90 wt .-% sinterable hard material a grain size between 0.6 and 5 microns and 3 to 20 wt .-% metallic binder having a particle size of 0.6 to 5 microns,
• b) introducing the powder starting material into a furnace,
• c) sintering the powder raw material first by subjecting the powder raw material to heat of a temperature at which the material of the metallic binder takes a doughy state, and then pressurized with a gas pressure at which the grain size of the individual particles of the powder raw material is reduced due to the reduction of the pore content of the starting material to the predetermined mean particle size distribution of the spheroidal sintered particles, and
• d) cooling the spheroidal sintered particles and removing the spheroidal sintered particles from the furnace.

If necessary, forming material bridges can be broken up between accumulated sintered particle assemblies without destroying the individual spheroidal sintered particles. This happens in a grinding device.

Below are some examples of selectable parameters of matrix powders. The powders are mixed in the indicated compositions. The specified particle size distributions are achieved by sieving. In this case, the values listed in tables are to be understood so that, for example, the proportion of particles greater than 180 μm is specified behind the specification "+180 μm" are and in the following line after the indication "+150 microns" the proportion of the particles which are larger than 150 microns but smaller than 180 microns.

As blocky ureas, broken carbides are used.

In general, a particle size distribution is preferred in which between 30 and 60 wt .-% of the hard materials in the particle size range of 106 to 250 microns and 40 to 70 wt .-% in the particle size range of -106 microns.

example 1

The matrix powder consists to 1-99% of spheroidal hard materials, which are present as WC-W ₂ C, or dense-sintered powder with closed porosity or as sintered pellets, both in the composition 94 wt .-% WC and 6 wt. -% Co, and in balance of broken carbides, either of WC-W ₂ C or as sintered, broken cermets in the composition 94 wt .-% WC and 6 wt .-% Co. The hard materials have the following particle size distribution: +180 μm 2% max. +150 μm 2-5% +106 μm 15-20% +75 μm 16-24% +45 μm 22-26% -45 μm 30-38%

Example 2

The matrix powder consists to 1-99% of spheroidal hard materials, which are present as WC-W ₂ C, or dense-sintered powder with closed porosity or pore-free or sintered pellets, both in the composition 94 wt .-% WC and 6 wt. % Co, and in balance of broken carbides, either from WC-W ₂ C or as sintered, broken cermets in the composition 94 wt .-% WC and 6 wt .-% Co, and a metallic powder in an amount 1-20 wt % of Ni in the grain size range -106 + 20 μm. The hard materials have the following particle size distribution: or or +212 μm 4% max. 2% max. 1% max +150 μm 35-47% 25-38% 8-16% +106 μm 15-27% 15-25% 12-22% +75 μm 8-15% 10-15% 12-22% +38 μm 15-28% 18-28% 25-35% -38 μm 6% max. 20% max. 20-32%

Example 3

The matrix powder consists to 1-99 wt .-% of a mixture of spheroidal hard materials and in balance of broken carbides. The mixture of spheroidal hard materials consists of carbides (WC-W ₂ C), and / or closed-sintered powders of closed porosity or nonporous and / or sintered pellets, both in the composition 94 wt% WC and 6 wt% Co The broken carbides consist of either WC-W ₂ C or are present as sintered, broken cermets in the composition of 94% by weight of WC and 6% by weight of Co. The particle size distribution of this mixture is as in Example 1.

Example 4

The matrix powder consists of 1-99 wt .-% of a mixture of spheroidal hard materials and in balance of broken carbides and a metallic powder in an amount 1-20 wt .-%. The powder consists of Ni in the particle size range -106 + 20 μm. The mixture of the spheroidal hard materials consists of carbides of WC-W ₂ C, and / or dense-sintered powders with closed porosity or non-porous and / or sintered pellets, each in the composition 94 wt .-% WC and 6 wt .-% Co. The broken carbides are WC-W ₂ C, or are present as sintered, crushed cermets in the composition of 94% by weight of WC and 6% by weight of Co. The hard material mixture has a particle size distribution as in Example 2.

A wear-resistant component is produced from the matrix powder in a manner known per se to those skilled in the art by filling the matrix powder into a mold and vibrating it under vibration. Then a suitable solder is added and the mold is heated in the oven, whereby the solder melts and infiltrates the matrix powder. After cooling, such a wear-resistant component has arisen, for example a drill bit. This manufacturing process is for example in the US 5733,664 described. The depth from the surface into which the infiltrant enters is called the depth of infiltration. This is preferably more than 30 mm.

The wear-resistant component thus formed has a high abrasion, erosion and fatigue strength in use due to the spheroidal hard body used therein.

Claims (17)

A matrix powder for the production of components for wear protection applications, which consists of hard material present in powder form and optionally a metallic powder, characterized in that part of the hard material is in the form of spheroidal hard material particles, and part of the hard material is in the form of broken carbides, wherein 30 and 60 wt .-% of the hard materials in the particle size range of 106 to 250 microns and 40 to 70 wt .-% in the particle size range of -106 microns. A matrix powder according to claim 1, wherein the grain sizes of the broken carbides are between 3 and 250 μm. Matrix powder according to one of claims 1 or 2, wherein the spheroidal hard material particles have a particle size between 20 and 250 microns. A matrix powder according to any one of the preceding claims, wherein the spheroidal hard material particles are present in a concentration of at least 5% by weight in the matrix powder. Matrix powder according to claim 4, wherein the spheroidal hard material particles in a concentration of at least 30 wt .-%, more preferably more than 50 wt .-%, in the matrix powder. A matrix powder according to any one of claims 1 to 5, wherein the matrix powder contains broken carbides in a concentration of at least 5% by weight. A matrix powder according to any one of the preceding claims, wherein the metallic powder is present in a concentration of 1 to 12% by weight. A matrix powder according to claim 7, wherein the metallic powder consists of Co, Ni, Cr, W, Cu or Fe or a mixture or alloy of these substances. A matrix powder according to claim 7 or 8, wherein the grain sizes of the metallic powder are between 20 and 150 μm. A matrix powder according to any one of the preceding claims, wherein the spheroidal hard materials are carbides of at least one of the metals W, Cr, Mo, Nb, V or Ti. A matrix powder according to any one of the preceding claims, wherein the spheroidal hard materials are dense sintered closed porosity powders or non-porous densely sintered powders based on carbides of the metals W, Cr, Mo, Nb, V or Ti or mixtures thereof with a metallic binder based on Co, Cr, Ni or Fe or mixtures or alloys thereof. A matrix powder according to any one of the preceding claims, wherein the spheroidal hard materials are sintered pellets based on carbides of the metals W, Cr, Mo, Nb, V or Ti or mixtures thereof and a metallic binder based on Co, Cr, Ni, Fe or mixtures or alloys of these. A matrix powder according to any one of the preceding claims wherein the broken carbides are carbides of the metals W, Cr, Mo, Nb, V or Ti. A matrix powder according to any one of the preceding claims wherein the fractured carbides are sintered, crushed cermets based on carbides of metals W, Cr, Mo, Nb, V or Ti with a metallic binder based on Co, Cr, Ni or Fe or Mixtures or alloys of these are. A matrix powder according to any one of the preceding claims, wherein the spheroidal hard materials present in dense-sintered closed porosity or pore-free dense sintered powder form or in the form of sintered pellets comprise between 80 and 97% by weight of carbides, preferably tungsten carbide, and 3 to 20 wt .-% of metallic binder, preferably cobalt. Wear-resistant component made from a matrix powder according to any one of claims 1-15 and a metal-containing infiltrant. The component of claim 16, wherein the infiltration depth is greater than 30 mm.