IE870314L - Tungsten carbide/cobalt composite - Google Patents
Tungsten carbide/cobalt compositeInfo
- Publication number
- IE870314L IE870314L IE31487A IE31487A IE870314L IE 870314 L IE870314 L IE 870314L IE 31487 A IE31487 A IE 31487A IE 31487 A IE31487 A IE 31487A IE 870314 L IE870314 L IE 870314L
- Authority
- IE
- Ireland
- Prior art keywords
- cobalt
- atoms
- tungsten carbide
- composite layer
- friction
- Prior art date
Links
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 title claims description 21
- 239000010941 cobalt Substances 0.000 title claims description 19
- 229910017052 cobalt Inorganic materials 0.000 title claims description 19
- 239000002131 composite material Substances 0.000 title claims description 12
- UONOETXJSWQNOL-UHFFFAOYSA-N tungsten carbide Chemical compound [W+]#[C-] UONOETXJSWQNOL-UHFFFAOYSA-N 0.000 title claims description 7
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 14
- 229910052799 carbon Inorganic materials 0.000 claims description 14
- 239000000203 mixture Substances 0.000 claims description 11
- 239000000919 ceramic Substances 0.000 claims description 8
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 claims description 5
- 239000010937 tungsten Substances 0.000 claims description 5
- 229910052721 tungsten Inorganic materials 0.000 claims description 5
- 229910052751 metal Inorganic materials 0.000 claims description 4
- 239000002184 metal Substances 0.000 claims description 4
- 150000001247 metal acetylides Chemical class 0.000 claims description 4
- 239000002905 metal composite material Substances 0.000 claims description 4
- 239000011195 cermet Substances 0.000 claims 1
- 239000003795 chemical substances by application Substances 0.000 claims 1
- 238000000354 decomposition reaction Methods 0.000 claims 1
- 239000002245 particle Substances 0.000 description 18
- 238000012360 testing method Methods 0.000 description 16
- 125000004429 atom Chemical group 0.000 description 15
- 239000000853 adhesive Substances 0.000 description 6
- 230000001070 adhesive effect Effects 0.000 description 6
- 239000011230 binding agent Substances 0.000 description 6
- 238000012546 transfer Methods 0.000 description 6
- 229910000831 Steel Inorganic materials 0.000 description 3
- 230000008901 benefit Effects 0.000 description 3
- 125000004432 carbon atom Chemical group C* 0.000 description 3
- 239000011248 coating agent Substances 0.000 description 3
- 238000000576 coating method Methods 0.000 description 3
- 239000006185 dispersion Substances 0.000 description 3
- 239000010959 steel Substances 0.000 description 3
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 2
- 239000005557 antagonist Substances 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 230000008646 thermal stress Effects 0.000 description 2
- NRTOMJZYCJJWKI-UHFFFAOYSA-N Titanium nitride Chemical compound [Ti]#N NRTOMJZYCJJWKI-UHFFFAOYSA-N 0.000 description 1
- 238000005299 abrasion Methods 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 229910010293 ceramic material Inorganic materials 0.000 description 1
- 150000001869 cobalt compounds Chemical class 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 238000012937 correction Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 239000000314 lubricant Substances 0.000 description 1
- 238000005461 lubrication Methods 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 238000010298 pulverizing process Methods 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 230000035882 stress Effects 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
- 238000005979 thermal decomposition reaction Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C29/00—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides
- C22C29/02—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides based on carbides or carbonitrides
- C22C29/06—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides based on carbides or carbonitrides based on carbides, but not containing other metal compounds
- C22C29/067—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides based on carbides or carbonitrides based on carbides, but not containing other metal compounds comprising a particular metallic binder
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C29/00—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides
- C22C29/02—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides based on carbides or carbonitrides
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Sliding-Contact Bearings (AREA)
- Other Surface Treatments For Metallic Materials (AREA)
- Lubricants (AREA)
- Laminated Bodies (AREA)
Description
9 5 41
1
4
The invention relates to a ceramic metal composite layer with improved frictional properties, comprising carbides of tungsten and of cobalt.
Ceramics and ceramic/metal composites or cermets have 05 intrinsic properties of hardness, resistance to elevated temperatures and chemical inertness which make them suitable for certain mechanical applications (layers, abutments, hermetic sealing adjuncts) and especially when the expected temperatures of use (cylinders of thermal 10 motors for example) or the environment (abrasive atmospheres) rule out conventional solutions such as the use of metals resistant to corrosion and suitably lubricated.
Ceramics and cermets, in the expected conditions of use (dry friction or with uncertain lubrication) generally present coefficients of friction considerably greater than 0.1, which is the maximum value acceptable for many applications, since greater values lead to excessive heating by reason of the density of energy brought into play, or more simply lead to high losses which cancel the advantages expected from working at high temperature for example.
The study of the frictions! properties of cermets leads to the following conclusions.
The inferior frictional properties of cermets appear to be due in great part to the metal which constitutes the binder, and which itself presents mediocre or bad tribo-
logical properties. With a binder content of 10% there is
\
often observed a typical metallic behaviour in conditions of friction, with the formation of we Ids, adhesive wear and transfer of material.
Nevertheless, since the metallic binder has for its premier role the task of reducing the fragility which characterizes ceramic materials, reduction of binder content improves the coefficient of friction and reduces the adhesive type wear, but increases the fragility or brittleness of the layers, with a lessening of the resistance to mechanical wear as a coro11ary.
But the applicant has discovered that by including free carbon in the material of the ceramic metal layer, it is possible practically to suppress the effect of the metallic binder on resistance to wear of the adhesive type, and at the same time to obtain remarkably low coefficients of friction.
In accordance with this discovery, the invention provides a ceramic metal composite layer with improved frictional properties, comprising the carbides of tungsten and of cobalt, characterized in that it comprises free carbon, its proportional composition being from 30 to 50 atoms of free carbon, from 3 to 12 atoms of cobalt, and tungsten carbide molecules to make up the balance of 100.
For preference the proportion of cobalt lies between 3 and 7 atoms per 100 particles, whether atoms or molecules.
The characteristics, advantages and properties of the composite layers of the invention will emerge, moreover, from the following description by way of example, with reference to the attached drawings in which:
05 Figure 1 is a diagram of the resistance to seizing and wear of composite layers as a function of their composition;
Figure 2 is a diagram of the measured coefficients of friction of layers as a function of the com-10 pressive force applied.
It is pointed out that the layers were obtained by a procedure derived from the conventional preparation of tungsten/cobalt carbide composite layers by pulverization in a plasma arc, and that the carbon present in the free 15 state in the layers originates at least mainly from thermal decomposition of the tungsten carbide.
The frictional experiments were carried out on a tribo-metric machine, in which a rotating ring is applied to an opposing plate under a pre-determined load, the speed of 20 rotation of the ring being regulated so that the linear sliding speed is 0.5 m/s.
Figure 1 gives the results of the preliminary experiments which were carried out to determine the most preferred compositions of the layers.
The abscissa represents the cobalt content, expressed as the number of atoms per 100 particles, and the ordinate represents a value of the tribological performances, expressed in arbitrary units, proportional to the frictional contact pressure threshold which produces irreparable 30 damage in the layer.
The results of tests carried out on layers which contain carbides of tungsten and of cobalt Co only are located
Y-
between the curves ^ and J}.
The results of tests carried out on layers additionally 05 comprising carbon in proportions of 30 to 50% correspond to the band contained between the curves c and d^; in this zone there is no appreciable correlation between the dispersion of the performances and the carbon contents.
For layers without carbon the performances are mediocre. 10 For low concentrations of cobalt, they rise with that concentration to stabilize at above 10 to 12 cobalt atoms per 100 particles. The dispersion of the results, represented by the spacing between the curves a_ and b_, remains smal1.
Observation of the samples after tests confirm that, below 10 atoms of Co per 100 particles, wear appears as mechanical abrasion (mechanical and thermal stresses at the point of contact); beyond 10 atoms per 100 particles the phenomenon of adhesive wear (seizing) preponderates.
For layers with 30 to 50 carbon atoms per 100 particles, the performances are very distinctly improved for cobalt contents comprising between 3 and 12 atoms per 100 particles. Moreover, for contents comprising between 3 and 7 atoms of cobalt per 100 particles, where the performance 25 maxima are found, the dispersion of the results, represented by the spacing between the curves c and _d, remains very low. so that the variations in compos it ion of the ternary layers hardly affect the performances at all. The reproducibility of the performances does not imply any very 30 precise control of the composition around the mean value.
Observations of the samples after test show that: - the presence of carbon limits, indeed suppresses,
adhesive wear, up to cobalt contents as high as 16 to 18 atoms per 100 particles. This adhesive wear reappears for higher cobalt concentrations.
The best performances arise with a cobalt content of about i
4 to 5 cobalt atoms per 100 particles, ie for a concentration at which, in the absence of carbon, the layers are significantly affected by mechanical wear (due to their sensitivity to mechanical and thermal stresses).
It has been demonstrated by micrographic tests, that the friction of the covered ring on the opposing plate creates, at the interface, a superficial film or transfer film, having a high carbon content, which limits the intrinsic action of the metallic binders. These transfer films benefit from the superior mechanical qualities of the substrate of tungsten carbide (hardness and Young's modulus) which are not affected by the high temperatures developed at the interface by the friction. These transfer films possess excellent resistance to mechanical stresses, in compression and in shear.
It will be seen that, after a running-in friction has established the transfer film, the cobalt present in the composite layer can undergo physicochemical changes without adverse repercussions on function and longevity. It even seems, on the contrary, that the formation of cobalt compound could be beneficial, because these compounds in general have better tribological properties.
In addition it has been established that at less than 30 carbon atoms per 100 particles, the transfer films are insufficiently developed, although above 50 carbon atoms per 100 particles, the composite layer has a reduced cohesion.
The tests on composite layers have subsequently given information on the determination of coefficient of friction r
under increasing loads.
*
The tests were carried out on a tribometric machine under 05 the following conditions:
- a cover was applied to the rotating ring
I
- the opposing plate was of steel 35 CD4 quench-tempered
- sliding speed 0.5 m/s
- dry friction without use of an extraneous lubricant 10 - load increasing in steps of 100 N from 100 N up to
1000 N, which corresponds to 100-340 N/mm in hertz contact pressure.
The composition of the sample I of the invention was Co:
4 atoms per 100 particles, C: 50 atoms per 100 particles. 15 Comparative tests were made with coverings of compositions located outside the scope of the invention.
Sample II: Co 10 atoms per 100 particles; C 33 atoms per 100 particles
Sample III: Co 20 atoms per 100 particles; C 30 atoms per 20 100 particles.
The results are given in Figure 2, each curve bearing the reference of the corresponding sample.
Sample I has a coefficient of friction of about 0.1 for a load of 100 newtons reducing to 0.07 under 400 N and 0.06 25 under 1000 N.
At the end of the test the wear was negligible. It is inferred from these results that the acceptable specific o
pressure is greater than 340 N/mm (this value representing the maximum load of the machine used).
By comparison sample II exhibits under 100 N a coefficient of friction of 0.15, which increases more than linearly with load, to reach 0.18 under 500 N.
Sample III exhibits a coefficient of friction of 0.2 under 100 N, which increases very rapidly with load, to exceed 0.4 under 200 N.
A third series of tests was carried out to estimate the influence of the opposing or antagonist frictional surface. The rotating ring was in every case of the same composition
I
as in sample I.
Test IV was done on a plate provided with a coating of the same composition as the ring.
Test V was done with a steel plate provided with a coating of titanium nitride.
Test VI on a plate of steel Z30 C 13.
Test VII on a plate of sintered alumina.
The results are given in the following table-
Table - Coefficients of friction
1 Load P (N) 1 Test | |
number 1100 j 200 !300 1400 1500 |600 |700 1800 |900 [1000| I I I I I I I I I I I IV |0.1011.10|0.08|0.07|0.06|0.06|0.06|0.06|0.06|0.06 | V |0.15|0.12|0.08|0.08|0.06|0.05|0.05|0.05(0.05|0.05|
VI |0.15|0.12|0.11|0.12|0.08|0.05|0.05|0.05|0.04|0.04|
VII |0.16|0.12|0.10|0.09|0.08|0.08|0.08|0.07|0.07|0.07 |
It follows from this table that, if correction is made for values related to the running-in period, all the coefficients of friction are of the same order of magnitude, whatever the nature of the antagonist layer of coating according to the invention. Particular note should be made of the advantageous behaviour of composite layers of the invention in friction against sintered alumina.
It should be recalled that tests I and IV-V11 were carried out with increasing load. It will be observed that if, subsequently, the load is caused to decrease, substantially the same coefficients of friction are obtained for the same 05 loads; in particular, in the case where the load is caused to decrease, an increase of the coefficient of friction in the range 500-300 N is observed.
The invention, of course, is not limited to the examples described, but includes all embodiments within the scope of 10 the claims.
Claims (5)
1. A ceramic metal composite layer with improved frictional properties, comprising carbides of tungsten ahd of cobalt, and containing free carbon, its proportional composition being from 30 to 50 atoms of free carbon, from 3 to 12 atoms of cobalt, and molecules of tungsten carbide to make up the balance of 100.
2. A composite layer as claimed in claim 1, wherein the proportional composition comprises from 3 to 7 atoms of cobalt.
3. A composite layer as claimed in claim 2, wherein the proportional composition substantially comprises 50 atoms of free carbon. 4 atoms of cobalt and 46 molecules of tungsten carbide.
4. A composite layer as claimed in any of claims 1 to 3, -wherein the free carbon content arises, at least to its v, greater extent, from the decomposition of tungsten carbide. ( \
5. \a ceramic metal (cermet) composite layer with improved frictional properties, as claimed in claim 1, substantially as herein described. Dated this the 6th day of February 1987 BY: T0MKINS & CO. Applicants Agents signed:
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FR8601676A FR2594143B1 (en) | 1986-02-07 | 1986-02-07 | TUNGSTEN CARBIDE / COBALT COMPOSITE WITH IMPROVED FRICTIONAL PROPERTIES |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| IE870314L true IE870314L (en) | 1987-08-07 |
| IE59541B1 IE59541B1 (en) | 1994-03-09 |
Family
ID=9331896
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| IE31487A IE59541B1 (en) | 1986-02-07 | 1987-02-06 | Tungsten carbide/cobalt composite having improved frictional properties |
Country Status (5)
| Country | Link |
|---|---|
| EP (1) | EP0237376B1 (en) |
| DE (1) | DE3761149D1 (en) |
| ES (1) | ES2011803B3 (en) |
| FR (1) | FR2594143B1 (en) |
| IE (1) | IE59541B1 (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2671382B1 (en) * | 1991-01-07 | 1994-12-23 | Jaeger | MECHANICAL SEALING FOR WATER PUMP ROTATING SHAFT FOR AUTOMOBILE. |
| US6857861B2 (en) | 2002-05-15 | 2005-02-22 | Kennametal Inc. | Ring for concrete pump |
| US6929426B2 (en) | 2003-02-19 | 2005-08-16 | Kennametal Inc. | Indexable cutting tool |
| US7070363B2 (en) | 2004-07-15 | 2006-07-04 | Kennametal Inc. | Cutting insert for high-speed milling cutter |
| FR3059757B1 (en) | 2016-12-07 | 2018-11-16 | H.E.F. | FRICTION PIECE, MECHANICAL SYSTEM COMPRISING SUCH FRICTION PIECE, AND METHOD OF IMPLEMENTING THE SAME |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2117731B2 (en) * | 1967-10-11 | 1974-08-23 | Anvar |
-
1986
- 1986-02-07 FR FR8601676A patent/FR2594143B1/en not_active Expired
-
1987
- 1987-02-04 EP EP19870400255 patent/EP0237376B1/en not_active Expired
- 1987-02-04 ES ES87400255T patent/ES2011803B3/en not_active Expired - Lifetime
- 1987-02-04 DE DE8787400255T patent/DE3761149D1/en not_active Expired - Lifetime
- 1987-02-06 IE IE31487A patent/IE59541B1/en not_active IP Right Cessation
Also Published As
| Publication number | Publication date |
|---|---|
| FR2594143B1 (en) | 1988-05-27 |
| FR2594143A1 (en) | 1987-08-14 |
| EP0237376B1 (en) | 1989-12-13 |
| ES2011803B3 (en) | 1990-02-16 |
| DE3761149D1 (en) | 1990-01-18 |
| EP0237376A1 (en) | 1987-09-16 |
| IE59541B1 (en) | 1994-03-09 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MM4A | Patent lapsed |