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Sulfur Containing Alpha-Alumina Coated Cutting Tool

a technology of alpha-alumina and cutting tools, applied in manufacturing tools, other chemical processes, coatings, etc., can solve the problems of high deposition rate, inability to control phase content, and pronounced dog-bone

Inactive Publication Date: 2014-06-26
WALTER AG
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention provides a coated cutting tool with a layer of α-Al2O3 that has improved cutting properties, resistance to chipping and crater wear, and lower friction with the workpiece compared to previous tools.

Problems solved by technology

Besides the fact that it was not possible to control the phase content, this early Al2O3 deposition process also suffered from a pronounced dog-bone-effect, i.e. the deposition rate was higher on the edges than on the flat surfaces of the substrate.

Method used

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  • Sulfur Containing Alpha-Alumina Coated Cutting Tool
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Examples

Experimental program
Comparison scheme
Effect test

example 1

α-Al2O3 Coatings

[0038]Cemented carbide substrates for cutting inserts with a composition of 6.0 wt % Co and balance WC (hardness about 1600 HV) were coated with a Ti(C,N) layer by applying MT-CVD using 0.6 vol % CH3CN, 3.8 vol % TiCl4, 20 vol % N2 and balance H2. The thickness of the Ti(C,N) MT-CVD layer was about 5 μm.

[0039]Onto this Ti(C,N) layer of separate substrate samples different layers consisting of about 8 μm α-Al2O3 were deposited. The coating parameters are given in Table 1, and the texture coefficients, TC(0 0 12), measured by X-ray diffraction, and the sulphur concentrations in the α-Al2O3 coatings, measured by SIMS, are given in Table 2.

[0040]The deposition of α-Al2O3 was started by depositing a 0.05 μm to about 1 μm, preferably 0.5 μm to about 1 μm, thick bonding layer on top of the MTCVD layer from the system H2—N2—CO—TiCl4—AlCl3 at a pressure of 50 to 100 mbar. For the preparation of the bonding layer the MTCVD layer was treated with a gas mixture of 3 vol % TiCl4,...

example 2

Edge Toughness Tests

[0044]The samples 1a to 4b of Example 1 were tested with respect to edge toughness (chipping resistance) in longitudinal turning of cast iron (GG25) using the following cutting parameters:

Work piece: GG25; cylindrical bar

Insert type: SNUN

Cutting speed: vc=400 m / min

Feed (f)=0.4 mm / rev

Depth of cut: ap=2.0 mm

Remarks: dry turning

[0045]The inserts were inspected after 2 and 4 minutes of cutting. As shown in Table 3, compared to the coating of the prior art, the edge toughness of the samples was considerably enhanced when the coating was produced according to this invention.

TABLE 3Edge ToughnessFlaking of the edge line (%)Flaking of the edge line (%)Coatingafter 2 minutesafter 4 minutes1a22341b18322a18412b12323a19293b X283c X044a18334b X03X = invention

example 3

Turning Tests

[0046]The samples 6, 8, 10 and 12 of Example 1 were tested in carbon steel (C45) without coolant using the following cutting parameters:

Work piece: C45

Insert type: WNMG080412-NM4

Cutting speed: vc=280 m / min

Feed (f)=0.32 mm / rev

Depth of cut: ap=2.5 mm

Remarks: dry turning

[0047]The end of tool life criterion was flank wear >0.3 mm. Three edges of each variant were tested.

TABLE 4Turning Test resultsCoatingTool Life (min) 613.2 815.510 X21.312 X32.2X = invention

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Abstract

Cutting tool insert has a substrate and a coating of one or more refractory layers of which at least one layer is an α-Al2O3 layer having thickness of 1 to 25 μm, sulphur content of more than 100 ppm analysed by Secondary Ion Mass Spectroscopy (SIMS), and texture coefficient TC (0 0 12)>4 for the (0 0 12) growth direction.The at least one α-Al2O3 layer is deposited by chemical vapour deposition (CVD) using reaction gases comprising H2, CO2, AlCl3 and X, with X being H2S, SO2, SF6, or combinations thereof, and optional additions of N2 and Ar. The amount of X is at least 1.0 vol-% of the total volume of gases in the reaction chamber. The volume ratio of CO2 and X in the reaction chamber lies within the range of 1≦CO2 / X≦7 during deposition of the at least one α-Al2O3 layer.

Description

FIELD OF THE INVENTION[0001]The present invention relates to a cutting tool insert consisting of a substrate of cemented carbide, cermet, ceramics, steel or a superhard material such as cubic boron nitride (CBN) and a hard coating consisting of one or more refractory layers of which at least one layer is an α-Al2O3 layer containing sulphur and having a specified growth orientation defined by the texture coefficient, and a method of manufacturing the cutting tool insert.BACKGROUND OF THE INVENTION[0002]The early approaches to deposit Al2O3 on a substrate surface in a CVD process based on a AlCl3 / CO2 / H2 reaction gas mixture had a very low deposition rates in the order of about 0.2 μm / h on flat surfaces. Besides the fact that it was not possible to control the phase content, this early Al2O3 deposition process also suffered from a pronounced dog-bone-effect, i.e. the deposition rate was higher on the edges than on the flat surfaces of the substrate. U.S. Pat. No. 4,619,866 by Smith and...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): B24D3/34
CPCB24D3/34C23C16/403C23C16/52C23C30/005
Inventor STIENS, DIRKRUPPI, SAKARI
Owner WALTER AG
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