TiC-WC / TiC-TiN layered ceramic material and method for manufacturing the same

Abstract

The application relates to the field of layered ceramic materials, in particular to a TiC-based ceramic material with TiC-WC layers and TiC-TiN layers alternately stacked and a preparation method. The problem that the existing toughening method of the TiC-based ceramic material is difficult to consider the strength and the fracture toughness is solved. A TiC-WC / TiC-TiN layered ceramic material, a TiC-WC layer is composed of the following raw materials in mass percentage: TiC 60%-80%, WC 5%-25%, Mo 4%-8%, and Ni 5%-10%; and a TiC-TiN layer is composed of the following raw materials in mass percentage: TiC 60%-80%, TiN 5%-25%, Mo 5%-9%, and Ni 6%-10%. The TiC-WC / TiC-TiN layered ceramic material obtained by combining a dry pressing forming method and a vacuum hot-pressing sintering technology can consider the strength and the fracture toughness of the material, and the comprehensive mechanical properties of the TiC-based ceramic material are improved.

Description

Technical Field

[0001] This invention relates to the field of layered ceramic materials, specifically to TiC-based ceramic materials with alternating TiC-WC and TiC-TiN layers, and their preparation methods. Background Technology

[0002] TiC-based ceramic materials possess excellent properties such as high melting point, high hardness, high electrical conductivity, low density, and good corrosion and oxidation resistance, making them widely used not only in cutting and wear-resistant tools but also in mining, agriculture, and aerospace. However, due to their poor sintering properties, TiC-based ceramic materials still suffer from low fracture toughness in practical applications, making them prone to failure under complex working conditions. Therefore, improving the fracture toughness of TiC-based ceramic materials is crucial.

[0003] Currently, the main toughening methods for TiC-based ceramic materials include: adding metallic binder phases, adding reinforcing phases, adding other toughening materials, and creating layered structures with weak interfacial bonding. Adding metallic materials such as Ni, Mo, Al, and Fe can effectively improve the sinterability of TiC-based ceramic materials. During sintering, the liquid-phase metallic materials can fill the gaps and pores in the matrix material, increasing the material's density and effectively improving the fracture toughness of TiC. However, the addition of metallic materials will reduce the hardness of TiC. Adding reinforcing phases such as WC, VC, TiB2, Cr3C2, TiN, and HfC can form a core-shell structure with the TiC matrix phase, effectively improving the wettability between the ceramic and metallic phases in the material. Simultaneously, transition metal carbides can also form solid solution strengthening by solidifying with the matrix. These methods can improve the mechanical properties of TiC-based ceramic materials, but the fracture toughness is still generally low. Adding other toughening materials such as carbon fibers and carbon nanotubes can effectively increase the fracture toughness of ceramic materials through bridging and pull-out of carbon nanotubes and carbon fibers, but the material is prone to forming pores, which will worsen the mechanical properties of the ceramic materials. The weak interface bonding layered structure stacks Ti and other ductile interlayers with TiC matrix materials, and uses the plastic deformation of the ductile layer to dissipate fracture energy, effectively deflecting cracks and improving the fracture toughness of TiC materials. However, due to the addition of weak interlayers, the strength of the layered ceramics is reduced. Summary of the Invention

[0004] To address the problem that existing toughening methods for TiC-based ceramic materials struggle to balance strength and fracture toughness, this invention designs a TiC-WC / TiC-TiN layered ceramic material and provides its preparation method.

[0005] This invention is achieved using the following technical solution: a TiC-WC / TiC-TiN layered ceramic material, wherein the TiC-WC layer is composed of the following raw materials by mass percentage: TiC 60%-80%, WC 5%-25%, Mo 4%-8%, Ni 5%-10%; the TiC-TiN layer is composed of the following raw materials by mass percentage: TiC 60%-80%, TiN 5%-25%, Mo 5%-9%, Ni 6%-10%; the layer structure is designed as a symmetrical structure, that is, TiC-WC serves as the upper and lower surface layers.

[0006] In layered ceramic materials, the relative magnitude of the thermal expansion coefficients of each layer affects its stress state. To prevent interlayer stress coupling, the layer structure is designed as an odd-numbered symmetrical structure. At the same time, to ensure that the upper and lower surfaces of the material eventually form compressive stress, TiC-WC with a small thermal expansion coefficient is used as the surface layer.

[0007] The prepared TiC-based crystalline ceramic material has clear and smooth interfaces between adjacent layers and uniform grain size. The flexural strength of the TiC-based crystalline ceramic material ranges from 946.01 to 1203.46 MPa, and the fracture toughness ranges from 7.78 to 10.59 MPa·m. 1 / 2 Compared with existing toughening methods, it can balance both strength and fracture toughness.

[0008] A method for preparing a TiC-WC / TiC-TiN layered ceramic material includes the following steps: Step 1: Prepare materials. Weigh the raw materials required for the TiC-WC layer and the TiC-TiN layer according to the required material composition ratio for each layer. Pour them into two ball mill jars marked to distinguish the two layers. Add an appropriate amount of ethanol and WC alloy balls to the ball mill jars and perform ball milling.

[0009] Step 2, drying: Place the ball-milled slurry in a drying oven, dry it at a constant temperature, and then sieve it.

[0010] Step 3, layering: Weigh the required TiC-WC layer powder, pour it into the graphite mold, flatten and compact it. Then weigh the required TiC-TiN layer powder, pour it into the graphite mold, flatten and compact it. Repeat this operation until the required layered structure is complete.

[0011] Step 4, hot pressing sintering: The graphite mold containing the blank is placed in a vacuum hot pressing sintering furnace. Under the conditions of heating rate of 10℃ / min, sintering pressure of 30MPa, and sintering temperature of 1550℃-1650℃, the temperature is held for 30min-60min to obtain TiC-WC / TiC-TiN layered ceramic material.

[0012] Adding reinforcing phases such as WC and TiN to the TiC matrix can effectively improve the strength of TiC-based ceramic materials. When cracks are generated under external force, the compressive stress formed on the surface of the layered material will act on the crack tip, hindering crack propagation. At the same time, the bonding surfaces between the layers will deflect the passing cracks, consume a large amount of fracture energy, and improve the fracture toughness of the material. Therefore, TiC-WC / TiC-TiN layered ceramic materials can balance the strength and fracture toughness of the material.

[0013] This invention combines dry pressing and vacuum hot pressing sintering technology to prepare TiC-WC / TiC-TiN layered ceramic materials, which can balance the strength and fracture toughness of the materials, improve the comprehensive mechanical properties of TiC-based ceramic materials, and the preparation method is simple and low in cost. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the layered structure of the present invention.

[0015] Figure 2 This is a scanning electron microscope image of the TiC-WC / TiC-TiN layered ceramic material.

[0016] In the figure, the layered ceramic material is clearly divided into layers: the dark gray layer is the TiC-TiN layer, the light gray layer is the TiC-WC layer, and the white dashed line is the interface between adjacent layers. To facilitate observation of crack propagation in the layered ceramic material, a diamond-shaped indentation was made in the TiC-WC layer using a hardness tester. Cracks were generated at all four corners of the indentation. Since the cracks consume fracture energy when passing through the interface, the vertical cracks in the figure are shorter than the horizontal cracks, further verifying the toughening effect of the layered ceramic material. Detailed Implementation

[0017] The designed TiC-WC / TiC-TiN layered ceramic material will be further explained below with reference to specific examples.

[0018] Example 1: A TiC-WC / TiC-TiN layered ceramic material. The TiC-WC layer is composed of the following raw materials by mass percentage: TiC 70%, WC 15%, Mo 5%, Ni 10%; the TiC-TiN layer is composed of the following raw materials by mass percentage: TiC 70%, TiN 15%, Mo 5%, Ni 10%. The total thickness of the test sample was designed to be 3 mm, the diameter to be 45 mm, and the number of layers to be 7. The thickness ratio of a single TiC-WC layer to a single TiC-TiN layer was 1:3.

[0019] A method for preparing a TiC-WC / TiC-TiN layered ceramic material includes the following steps: Step 1: Prepare materials. Weigh the raw materials required for the TiC-WC layer and the TiC-TiN layer according to the required material composition ratio for each layer. Pour them into two ball mill jars marked to distinguish the two layers. Add an appropriate amount of ethanol and WC alloy balls to the ball mill jars and perform ball milling.

[0020] Step 2, drying: Place the ball-milled slurry in a drying oven, dry it at a constant temperature, and then sieve it.

[0021] Step 3, layering: Weigh the required TiC-WC layer powder, pour it into the graphite mold, flatten and compact it. Then weigh the required TiC-TiN layer powder, pour it into the graphite mold, flatten and compact it. Repeat this operation until the required layered structure is complete.

[0022] Step 4, hot pressing sintering: The graphite mold containing the blank is placed in a vacuum hot pressing sintering furnace. Under the conditions of heating rate of 10℃ / min, sintering pressure of 30MPa, and sintering temperature of 1550℃, it is held for 60min to obtain TiC-WC / TiC-TiN layered ceramic material.

[0023] Example 2: A TiC-WC / TiC-TiN layered ceramic material. The TiC-WC layer is composed of the following raw materials by mass percentage: TiC 65%, WC 20%, Mo 7%, Ni 8%; the TiC-TiN layer is composed of the following raw materials by mass percentage: TiC 65%, TiN 20%, Mo 7%, Ni 8%. The total thickness of the test sample was designed to be 3 mm, the diameter to be 45 mm, and the number of layers to be 7. The thickness ratio of a single TiC-WC layer to a single TiC-TiN layer was 1:3.

[0024] A method for preparing a TiC-WC / TiC-TiN layered ceramic material includes the following steps: Step 1: Prepare materials. Weigh the raw materials required for the TiC-WC layer and the TiC-TiN layer according to the required material composition ratio for each layer. Pour them into two ball mill jars marked to distinguish the two layers. Add an appropriate amount of ethanol and WC alloy balls to the ball mill jars and perform ball milling.

[0025] Step 2, drying: Place the ball-milled slurry in a drying oven, dry it at a constant temperature, and then sieve it.

[0026] Step 3, layering: Weigh the required TiC-WC layer powder, pour it into the graphite mold, flatten and compact it. Then weigh the required TiC-TiN layer powder, pour it into the graphite mold, flatten and compact it. Repeat this operation until the required layered structure is complete.

[0027] Step 4, hot pressing sintering: The graphite mold containing the blank is placed in a vacuum hot pressing sintering furnace. Under the conditions of heating rate of 10℃ / min, sintering pressure of 30MPa, and sintering temperature of 1600℃, it is held for 45min to obtain TiC-WC / TiC-TiN layered ceramic material.

[0028] Example 3: A TiC-WC / TiC-TiN layered ceramic material. The TiC-WC layer is composed of the following raw materials by mass percentage: TiC 60%, WC 25%, Mo 9%, Ni 6%; the TiC-TiN layer is composed of the following raw materials by mass percentage: TiC 60%, TiN 25%, Mo 9%, Ni 6%. The total thickness of the test sample was designed to be 3 mm, the diameter to be 45 mm, and the number of layers to be 7. The thickness ratio of a single TiC-WC layer to a single TiC-TiN layer was 1:3.

[0029] A method for preparing a TiC-WC / TiC-TiN layered ceramic material includes the following steps: Step 1: Prepare materials. Weigh the raw materials required for the TiC-WC layer and the TiC-TiN layer according to the required material composition ratio for each layer. Pour them into two ball mill jars marked to distinguish the two layers. Add an appropriate amount of ethanol and WC alloy balls to the ball mill jars and perform ball milling.

[0030] Step 2, drying: Place the ball-milled slurry in a drying oven, dry it at a constant temperature, and then sieve it.

[0031] Step 3, layering: Weigh the required TiC-WC layer powder, pour it into the graphite mold, flatten and compact it. Then weigh the required TiC-TiN layer powder, pour it into the graphite mold, flatten and compact it. Repeat this operation until the required layered structure is complete.

[0032] Step 4, hot pressing sintering: The graphite mold containing the blank is placed in a vacuum hot pressing sintering furnace. Under the conditions of heating rate of 10℃ / min, sintering pressure of 30MPa, and sintering temperature of 1650℃, it is held for 30min to obtain TiC-WC / TiC-TiN layered ceramic material.

Claims

1. A TiC-WC / TiC-TiN layered ceramic material, wherein the TiC-WC layer is composed of the following raw materials in the following mass percentages: The TiC-TiN layer is composed of the following mass percentages of raw materials: TiC 60%-80%, WC 5%-25%, Mo 5%-8%, and Ni 5%-10%. The layer structure is designed as a symmetrical structure, with TiC-WC as the upper and lower surface layers. The thickness ratio of a single TiC-WC layer to a single TiCTiN layer is 1:

3. The preparation method is as follows: (1) Prepare materials. Weigh the raw materials required for TiC-WC layer and TiC-TiN layer according to the component ratio of each layer. Pour them into two ball mill jars marked to distinguish the two layers. Add an appropriate amount of ethanol and WC alloy balls to the ball mill jars and ball mill them. (2) Dry. Place the ball-milled slurry in a drying oven and dry it at a constant temperature. Then sieve it. (3) Stack. Weigh the required TiCWC layer powder, pour it into a graphite mold, spread it flat and compact it. Then weigh the required TiC-TiN layer powder, pour it into a graphite mold, spread it flat and compact it. Repeat this operation until the required layered structure is complete. (4) Hot pressing sintering involves placing a graphite mold containing the blank into a vacuum hot pressing sintering furnace, and holding it at a heating rate of 10℃ / min, a sintering pressure of 30MPa, and a sintering temperature of 1550℃-1650℃ for 30min-60min to obtain TiC-WC / TiC-TiN layered ceramic materials.

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