A method for controlling the removal of β-layer from a CVD-coated CNC blade substrate

Abstract

The present invention discloses a method for regulating the de-β layer of a CVD-coated CNC insert substrate, which relates to the technical field of cemented carbide. Specifically, a WC-(Ti,W)C-Ti(C,N)-(Ta,Nb)C-Co gradient cemented carbide is prepared by sintering in a denitrified atmosphere at 1450°C using WC, Co, Ti(C,N), (Ti,W)C, and (Ta,Nb)C powders as raw materials. The method achieves a balance of components by increasing the Ti(C,N) content and correspondingly reducing the (Ti,W)C content, thereby regulating the thickness of the de-β layer without changing the overall performance of the alloy. In seasons with high humidity, the Ti(C,N) content is increased to reduce the influence of humidity on the thickness of the de-β layer.

Description

Technical Field

[0001] The invention relates to the technical field of cemented carbide, and in particular to a method for controlling the removal of a β layer from a CVD-coated numerically controlled blade substrate. Background Art

[0002] When de-β-layered gradient cemented carbide is used as the base material for coated inserts, its highly tough surface layer can hinder crack propagation, thereby extending the service life of the insert. Generally, nitrogen-containing cemented carbide raw materials are used to prepare de-β-layered gradient cemented carbide. That is, nitrogen-containing cubic phases such as TiN or Ti(C,N) are directly added to ordinary cemented carbide raw materials such as WC, cobalt, and (Ti,W)C. The thickness of the de-β-layer is closely related to its formation mechanism. It is currently believed that the formation mechanism is: during the liquid phase sintering process of WC-Ti(C,N)-Co cemented carbide, Ti(C,N) decomposes, N atoms move to the surface of the alloy, and Ti atoms migrate inward due to the strong thermodynamic coupling between N atoms and Ti atoms, forming a tough zone lacking cubic phase carbides on the alloy surface, namely the de-β-layer. The thickness of the de-β-layer affects the performance and life of the insert, so how to accurately control its preparation process is a research focus.

[0003] Existing mechanistic analyses have focused on the influence of alloy composition, particle size, nitrogen partial pressure, and sintering temperature. Compacts made from the same mixture and sintered under the same sintering curve can sometimes show different thicknesses of the de-β layer at different locations in the sintering furnace, indicating that the sintering atmosphere within the furnace affects the thickness of the de-β layer formed in the alloy.

[0004] Extensive production practice has proven that the de-β layer is related to the carbon content on the alloy surface. This is primarily due to the influence of ambient humidity and the sintering atmosphere on the carbon content on the alloy surface, which in turn affects the thickness of the de-β layer. The PEG forming agent in the alloy compact easily absorbs moisture, which reduces the carbon content in the alloy and leads to unstable de-β layer thickness. Although the production process is maintained at a constant temperature and humidity, the movement of personnel and products in and out will affect the humidity to varying degrees, especially in environments with wide humidity swings between winter and summer. Summary of the Invention

[0005] The purpose of the present invention is to solve at least one of the technical problems existing in the prior art and to provide a method for controlling the removal of the β layer from a CVD coated CNC blade substrate.

[0006] The technical solutions of the present invention are as follows:

[0007] A method for regulating the removal of a β layer from a CVD-coated CNC insert substrate comprises the following steps: using WC, Co, Ti(C,N), (Ti,W)C, and (Ta,Nb)C powders as raw materials and sintering in a denitrified atmosphere to obtain a WC-(Ti,W)C-Ti(C,N)-(Ta,Nb)C-Co gradient cemented carbide; wherein the amount of Ti(C,N) added is varied according to the humidity of the preparation environment, thereby regulating the obtained gradient cemented carbide to have a mechanical property variation of 0-1%.

[0008] Preferably, the added amount of Ti(C,N) varies linearly with the humidity of the preparation environment.

[0009] Preferably, when the humidity of the preparation environment changes by 30%, the added mass of Ti(C,N) changes by 0.1%.

[0010] Preferably, when the humidity is 30%, the addition amount of Ti(C,N) is 0.9wt%, the addition amount of (Ti,W)C is 5.0wt%, the addition amount of (Ta,Nb)C and Co is quantitative, and the balance is WC;

[0011] When the humidity is 60%, the addition amount of Ti(C,N) is 1.0wt%, the addition amount of (Ti,W)C is 4.8wt%, the addition amount of (Ta,Nb)C and Co is quantitative, and the balance is WC;

[0012] When the humidity is 90%, the addition amount of Ti(C,N) is 1.1wt%, the addition amount of (Ti,W)C is 4.6wt%, the addition amount of (Ta,Nb)C and Co is quantitative, and the balance is WC.

[0013] Preferably, the addition amount of the (Ta, Nb)C and Co is 10-15 wt%.

[0014] Preferably, the preparation method of the gradient cemented carbide is as follows:

[0015] The WC, Co, Ti(C, N), (Ti, W)C and (Ta, Nb)C powders are weighed, added with a forming agent, mixed evenly, ball-milled, dried, pressed and sintered to obtain the product.

[0016] Preferably, the sintering temperature is 1400-1500°C.

[0017] The beneficial effects of the present invention are as follows: the preparation method of the β-delayered CVD-coated CNC blade substrate of the present invention can achieve the adjustment of the thickness of the β-delayered alloy by simply regulating the alloy composition without affecting the overall alloy performance, and can more effectively control the stability of the alloy performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a microscopic image of the sample of Comparative Example 1;

[0019] Figure 2 This is a microscopic image of the sample of Example 1;

[0020] Figure 3 This is a microscopic image of the sample of Example 2;

[0021] Figure 4 This is a microscopic image of the sample of Example 3. DETAILED DESCRIPTION

[0022] A method for regulating the removal of a β layer from a CVD-coated CNC insert substrate comprises the following steps: using WC, Co, Ti(C,N), (Ti,W)C, and (Ta,Nb)C powders as raw materials and sintering in a denitrified atmosphere to obtain a WC-(Ti,W)C-Ti(C,N)-(Ta,Nb)C-Co gradient cemented carbide; wherein the amount of Ti(C,N) added is varied according to the humidity of the preparation environment, thereby regulating the obtained gradient cemented carbide to have a mechanical property variation of 0-1%.

[0023] Specifically, the addition amount of the Ti(C,N) changes linearly with the humidity of the preparation environment.

[0024] Preferably, when the humidity of the preparation environment changes by 30%, the added mass of Ti(C,N) changes by 0.1%.

[0025] Specifically, when the humidity is 30%, the addition amount of Ti(C,N) is 0.9wt%, the addition amount of (Ti,W)C is 5.0wt%, the addition amount of (Ta,Nb)C and Co is quantitative, and the balance is WC;

[0026] When the humidity is 60%, the addition amount of Ti(C,N) is 1.0wt%, the addition amount of (Ti,W)C is 4.8wt%, the addition amount of (Ta,Nb)C and Co is quantitative, and the balance is WC;

[0027] When the humidity is 90%, the addition amount of Ti(C,N) is 1.1wt%, the addition amount of (Ti,W)C is 4.6wt%, the addition amount of (Ta,Nb)C and Co is quantitative, and the balance is WC.

[0028] Preferably, the addition amount of the (Ta, Nb)C and Co is 10-15 wt%.

[0029] Preferably, the preparation method of the gradient cemented carbide is as follows:

[0030] The WC, Co, Ti(C, N), (Ti, W)C and (Ta, Nb)C powders are weighed, added with a forming agent, mixed evenly, ball-milled, dried, pressed and sintered to obtain the product.

[0031] Preferably, the sintering temperature is 1400-1500°C.

[0032] The following embodiments of the present invention are described in detail. The embodiments described below are exemplary and are only used to explain the present invention, and are not to be construed as limiting the present invention. Where specific techniques or conditions are not specified in the embodiments, the techniques or conditions described in the literature in this field or the product specifications are used. Where the manufacturer of the reagents or instruments is not specified, all are conventional products that can be obtained commercially.

[0033] PEG: polyethylene glycol.

[0034] Example 1

[0035] A method for regulating the removal of a β layer from a CVD-coated CNC blade substrate comprises weighing WC, Co, Ti(C, N), (Ti, W)C, and (Ta, Nb)C powders, adding a molding agent (PEG), mixing the mixture, ball milling, drying, pressing, and sintering the mixture at a sintering temperature of 1450° C. for 1 hour.

[0036] When the humidity of the preparation environment is 30%, the addition amount of Ti(C,N) is 0.9wt%, the addition amount of (Ti,W)C is 5.0wt%, the addition amount of (Ta,Nb)C is 4.0wt%, the addition amount of Co is quantitatively 6.0wt%, and the balance is WC.

[0037] Example 2

[0038] A method for regulating the removal of a β layer from a CVD-coated CNC blade substrate comprises weighing WC, Co, Ti(C, N), (Ti, W)C, and (Ta, Nb)C powders, adding a molding agent (PEG), mixing the mixture, ball milling, drying, pressing, and sintering the mixture at a sintering temperature of 1450° C. for 1 hour.

[0039] When the humidity of the preparation environment is 60%, the addition amount of Ti(C,N) is 1.0wt%, the addition amount of (Ti,W)C is 4.8wt%, the addition amount of (Ta,Nb)C is 4.0wt%, the addition amount of Co is quantitatively 6.0wt%, and the balance is WC.

[0040] Example 3

[0041] A method for regulating the removal of a β layer from a CVD-coated CNC blade substrate comprises weighing WC, Co, Ti(C, N), (Ti, W)C, and (Ta, Nb)C powders, adding a molding agent (PEG), mixing the mixture, ball milling, drying, pressing, and sintering the mixture at a sintering temperature of 1450° C. for 1 hour.

[0042] When the humidity of the preparation environment is 90%, the addition amount of Ti(C,N) is 1.1wt%, the addition amount of (Ti,W)C is 4.6wt%, the addition amount of (Ta,Nb)C is 4.0wt%, the addition amount of Co is quantitatively 6.0wt%, and the balance is WC.

[0043] Comparative Example 1

[0044] A method for regulating the removal of a β layer from a CVD-coated CNC blade substrate comprises weighing WC, Co, Ti(C, N), (Ti, W)C, and (Ta, Nb)C powders, adding a molding agent (PEG), mixing the mixture, ball milling, drying, pressing, and sintering the mixture at a sintering temperature of 1450° C. for 1 hour.

[0045] When the humidity of the preparation environment is 90%, the addition amount of Ti(C,N) is 0.9wt%, the addition amount of (Ti,W)C is 5.0wt%, the addition amount of (Ta,Nb)C is 4.0wt%, the addition amount of Co is quantitatively 6.0wt%, and the balance is WC.

[0046] The samples of Examples 1-3 and Comparative Example 1 were microscopically scanned. Figure 2-Figure 4 and Figure 1 The thickness of Comparative Example 1 is relatively thin, while the thickness of Examples 1-3 does not change much as the humidity increases. It can be seen that the adjustment of the component content can achieve the regulation of the thickness of the β layer (avoiding the influence of humidity on it), thereby making its mechanical properties slightly changed. At the same time, the alloy properties of Examples 1-3 and Comparative Example 1 were tested, and the test results are as follows:

[0047] Table 1 Sample composition and properties of Examples 1-3 and Comparative Example 1

[0048]

[0049] As can be seen from the above table, in different humidity environments, by adjusting the contents of Ti(C,N) and (Ti,W)C, Examples 1-3 obtain cemented carbides with different β-layer thicknesses, and the service life is increased by at least 20% relative to that of Comparative Example 1, thereby avoiding the influence of environmental humidity and ensuring the stability of the alloy performance.

[0050] In summary, the present invention achieves a balance of components by increasing the Ti(C, N) content and correspondingly reducing the (Ti, W)C content, thereby achieving the purpose of regulating the thickness of the de-β layer without changing the overall performance of the alloy. In seasons with high humidity, the Ti(C, N) content is increased to reduce the effect of humidity on the thickness of the de-β layer.

[0051] The above-described embodiments merely represent preferred implementations of the present invention. While the descriptions thereof are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make various other corresponding changes and modifications based on the technical solutions and concepts described above, and all such changes and modifications should fall within the scope of protection of the claims of the present invention.

Claims

1. A method for controlling the removal of the β layer from a CVD-coated CNC blade substrate, characterized in that: WC-(Ti,W)C-Ti(C,N)-(Ta,Nb)C-Co gradient cemented carbide was prepared by sintering in a denitrified atmosphere using WC, Co, Ti(C,N), (Ti,W)C, and (Ta,Nb)C powders as raw materials. The amount of Ti(C,N) added was varied according to the humidity of the preparation environment to achieve a gradient cemented carbide with a mechanical property variation of 0-1%. The amount of Ti(C,N) added varied linearly with the humidity of the preparation environment. The humidity change in the preparation environment is 30%, and the added mass change of Ti(C,N) is 0.1%; When the humidity is 30%, the addition amount of Ti(C,N) is 0.9wt%, the addition amount of (Ti,W)C is 5.0wt%, the addition amount of (Ta,Nb)C and Co is quantitative, and the balance is WC; When the humidity is 60%, the addition amount of Ti(C,N) is 1.0wt%, the addition amount of (Ti,W)C is 4.8wt%, the addition amount of (Ta,Nb)C and Co is quantitative, and the balance is WC; When the humidity is 90%, the addition amount of Ti(C,N) is 1.1wt%, the addition amount of (Ti,W)C is 4.6wt%, the addition amount of (Ta,Nb)C and Co is quantitative, and the balance is WC; The addition amount of (Ta, Nb) C and Co is 10-15wt%.

2. The method for controlling the removal of the β layer from a CVD-coated CNC blade substrate according to claim 1, characterized in that: The preparation method of the gradient cemented carbide is as follows: The WC, Co, Ti(C, N), (Ti, W)C and (Ta, Nb)C powders are weighed, added with a forming agent, mixed evenly, ball-milled, dried, pressed and sintered to obtain the product.

3. The method for controlling the removal of the β layer from a CVD-coated CNC blade substrate according to claim 1 or 2, characterized in that: The sintering temperature is 1400-1500°C.

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