Stock material or miscellaneous articles – All metal or with adjacent metals – Having metal particles
Reexamination Certificate
1997-09-12
2001-08-14
Kastler, Scott (Department: 1742)
Stock material or miscellaneous articles
All metal or with adjacent metals
Having metal particles
C428S553000, C428S699000, C204S192380
Reexamination Certificate
active
06274249
ABSTRACT:
BACKGROUND OF THE INVENTION
This description incorporates U.S. Pat. No. 5,709,784 by reference herein.
The present invention is directed on a tool with a tool body and a protective layer system, wherein the layer system comprises at least one layer of MeX, wherein
Me comprises titanium and aluminum,
X is at least one of nitrogen and of carbon.
Definition
The term Q
I
is defined as the ratio of the diffraction intensities I(200) to I(111), assigned respectively to the (200) and (111) plains in the X ray diffraction of a material using the &thgr;-2&thgr; method. Thus, there is valid Q
I
=I(200)/I(111). The intensity values were measured with the following equipment and with the following settings:
Siemens Diffractometer D500
Power:
Operating voltage: 30 kV
Operating current: 25 mA
Aperture Diaphragms:
Diaphragm position I: 1°
Diaphragm position II: 0.1°
Detector Diaphragm: Soller slit
Time constant: 4 s
2&thgr; angular speed: 0.05°/min
Radiation: Cu—K&agr;(0.15406 nm)
When we refer to “measured according to MS” we refer to this equipment and to these settings. Thereby, all quantitative results for Q
I
and I throughout this application have been measured by MS.
We understand by “tool body” the uncoated tool.
We understand under “hard material” a material with which tools which are mechanically and thermally highly loaded in operation are coated for wear resistance. Preferred examples of such materials are referred to below as MeX materials.
It is well-known in the tool-protecting art to provide wear resistant layer systems which comprise at least one layer of a hard material, as defined by MeX.
SUMMARY OF THE INVENTION
The present invention has the object of significantly improving the lifetime of such tools. This is resolved by selecting for said at least one layer a Q
I
value, for which there is valid
Q
I
≦2
and wherein the tool is a solid carbide end mill or a solid carbide ball nose mill or a cemented carbide gear cutting tool. Further, the value of I(111) is higher by a factor of at least 20 than the intensity noise average level as measured according to MS.
According to the present invention it has been recognised that the Q
I
values as specified lead to an astonishingly high improvement of wear resistance, and thus of lifetime of a tool, if such a tool is of the kind as specified.
Up to now, application of a wear resistant layer system of MeX hard material was done irrespective of interaction between tool body material and the mechanical and thermal load the tool is subjected to in operation. The present invention thus resides on the fact that it has been recognised that an astonishing improvement of wear resistance is realised when selectively combining the specified Q
I
value with the specified kind of tools, thereby realising a value of I(111) higher by a factor of at least 20 then the average noise intensity level, both measured with MS.
The inventively reached improvement is even increased if Q
I
is selected to be at most 1, and an even further improvement is realised by selecting Q
I
to be at most 0.5 or even to be at most 0.2. The largest improvements are reached if Q
I
is at most 0.1. It must be stated that Q
I
may drop towards zero, if the layer material is realised with a unique crystal orientation according to a vanishing diffraction intensity I(200). Therefore, there is not set any lower limit for Q
I
which is only set by practicability.
As is known to the skilled artisan there exists a correlation between hardness of a layer and stress therein. The higher the stress, the higher the hardness. Nevertheless, with rising stress, the adhesion to the tool body tends to diminish.
For the tool according to the present invention a high hardness is rather more important than the best possible adhesion. Therefore, the stress in the MeX layer is advantageously selected rather at the upper end of the stress range given below. These considerations limit in practice the Q
I
value exploitable.
In a preferred embodiment of the inventive tool, the MeX material of the tool is titanium aluminum nitride, titanium aluminum carbonitride or titanium aluminum boron nitride, whereby the two materials first mentioned are today preferred over titanium aluminum boron nitride.
In a further form of realisation of the inventive tool, Me of the layer material MeX may additionally comprise at least one of the elements boron, zirconium, hafnium, yttrium, silicon, tungsten, chromium, whereby, out of this group, it is preferred to use yttrium and/or silicon and/or boron. Such additional element to titanium and aluminum is introduced in the layer material, preferably with a content i, for which there is valid
0.05 at. %≦i≦60 at. %,
taken Me as 100 at %.
A still further improvement in all different embodiments of the at least one MeX layer is reached by introducing an additional layer of titanium nitride between the MeX layer and the tool body with a thickness d, for which there is valid
0.05 &mgr;m≦d≦5 &mgr;m.
In view of the general object of the present invention, which is to propose the inventive tool to be manufacturable at lowest possible costs and thus most economically, there is further proposed that the tool has only one MeX material layer and the additional layer which is deposited between the MeX layer and the tool body.
Further, the stress &sgr; in the MeX is preferably selected to be
2 GPa≦&sgr;≦8 GPa,
thereby most preferably with the range
4 GPa≦&sgr;≦6 GPa.
The content x of titanium in the Me component of the MeX layer is preferably selected to be
70 at %≧x≧40 at %,
thereby in a further preferred embodiment within the range
65 at %≧x≧55 at %.
On the other hand, the content y of aluminum in the Me component of the MeX material is preferably selected to be
30 at %≦y≦60 at %,
in a further preferred embodiment even to be
35 at %≦y≦45 at %.
In a still further preferred embodiment, both these ranges, i.e. with respect to titanium and with respect to aluminum are fulfilled.
The deposition, especially of the MeX layer, may be done by any known vacuum deposition technique, especially by a reactive PVD coating technique, as e.g. reactive cathodic arc evaporation or reactive sputtering. By appropriately controlling the process parameters, which influence the growth of the coating, the inventively exploited Q
I
range is realised.
To achieve excellent and reproducible adhesion of the layers to the tool body a plasma etching technology was used, as a preparatory step, based on an Argon plasma as described in U.S. Pat. No. 5,709,784, which document is integrated to this description by reference, with respect to such etching and subsequent coating.
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The Structure And Composition Of Ti-Zr-N, Ti-A1-Zr-N and Ti-A1-V-N Coatings, Knotek et al.; Materials Science and Engineering, Dec. 1988; pp. 481-488.
Interrelationship Between Processing, Coating Properties And Functional Properties of Steered ARC Physically Vapour Deposited (Ti,A1) N And (Ti,Nb) N Coatings; Roos et al.; Elsevier Sequoia; Dec. 1, 1990; pp. 547-556.
Effects of R.F. Bias And Nitrogen Flow Rates On The Reactive Sputtering Of TiA1N Films; Shew et al.; Elsevier; Dec. 1997; pp. 212-219.
Effects of High-Flux Low-Energy (20-100 eV) Ion Irradiation During Deposition On The Microstructure And Preferred Orientation of T
Braendle Hans
Shima Nobuhiko
Evenson, McKeown, Edwards & Lenahan P.L.L.C.
Kastler Scott
Unaxis Balzers Aktiengesellschaft
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