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Preparation method of h-BN/VC machinable ceramic

A ceramic, h-bn technology, applied in the field of h-BN/VC machinable ceramics, can solve the problem of low bending strength, achieve high strength, uniform microstructure, and excellent oxidation resistance

Inactive Publication Date: 2013-12-04
SHANDONG UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Therefore, the machinable ceramic materials prepared by the usual hybrid and chemical h-BN coating technology have low flexural strength

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0012] The first step: uniformly mix boric acid: urea in a weight ratio of 2:1, add 30% ethanol, heat treatment at 50°C in a closed container for 24 hours, and then stir for 30 minutes to make an esterification solution;

[0013] Step 2: Add 70% of VC ceramic powder with a particle size of 0.1μm to 30% esterification solution to make a ceramic slurry, and then use a spray granulator to make the above ceramic slurry into a bag with a diameter of 0.5mm Coated VC powder, nitriding the above-mentioned coated VC powder in a nitrogen atmosphere at a temperature of 600°C for 30 minutes to obtain h-BN coated VC ceramic powder, and h-BN coated VC ceramic powder at a pressure of 100MPa. The lower isostatic pressing is pressed into a ?60×10~20mm sheet green body, and then hot-pressed at 1700°C×30 minutes under a nitrogen atmosphere at 5MPa. Fired into h-BN / VC machinable ceramics.

[0014] The purity of the batching raw materials used in the experiment is industrial pure, and the bending...

Embodiment 2

[0016] The first step: uniformly mix boric acid: urea at a weight ratio of 2:1, add 45% ethanol, heat in a closed container at 70°C for 16 hours, and then stir for 20 minutes to make an esterification solution;

[0017] Step 2: Add 55% of VC ceramic powder with a particle size of 1 μm to 45% esterification solution to make a ceramic slurry, and then use a spray granulator to make the above ceramic slurry into a coating with a diameter of 0.2mm VC powder, nitriding the above coated VC powder in a nitrogen atmosphere at a temperature of 800°C for 45 minutes to obtain h-BN coated VC ceramic powder, and h-BN coated VC ceramic powder under a pressure of 150MPa. Press isostatically into a ?60×10~20mm flake green body, and then hot-press 50MPa under nitrogen atmosphere at 1800℃×105 minutes. Fire into h-BN / VC machinable ceramics.

[0018] The purity of the batching raw materials used in the experiment is industrial pure, and the bending strength of the obtained h-BN / VC machinable cer...

Embodiment 3

[0020] The first step: uniformly mix boric acid: urea in a weight ratio of 2:1, add 60% ethanol, heat treatment at 90°C in a closed container for 10 hours, and then stir for 10 minutes to make an esterification solution;

[0021] Step 2: Add 40% of VC ceramic powder with a particle size of 2μm to 60% esterification solution to make a ceramic slurry, and then use a spray granulator to make the above ceramic slurry into a coating with a diameter of 0.01mm VC powder, nitriding the above coated VC powder in a nitrogen atmosphere at a temperature of 1000°C for 60 minutes to obtain h-BN coated VC ceramic powder, and h-BN coated VC ceramic powder under a pressure of 200MPa. Press isostatically into a ?60×10~20mm sheet green body, and then hot-press 100MPa under a nitrogen atmosphere at 1850℃×180 minutes. Fire into h-BN / VC machinable ceramics.

[0022] The purity of the batching raw materials used in the experiment is industrial pure, and the bending strength of the obtained h-BN / VC ...

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Abstract

The invention relates to a preparation method of an h-BN / VC machinable ceramic. The method is characterized in that the h-BN / VC machinable ceramic is obtained via hot-pressing and sintering after a cold isostatic pressing process by using h-BN coated VC ceramic powder. The method comprises the steps of mixing boric acid, urea and ethanol in a sealed container according to a proportion to form an esterification solution; adding VC ceramic powder in the esterification solution to form ceramic slurry; making the ceramic slurry into coated VC powder by using a spray granulator; nitriding the coated VC powder to obtain the h-BN coated VC ceramic powder; pressing the h-BN coated VC ceramic powder into sheet green bodies via an isostatic pressing process; hot-pressing the sheet green bodies under a nitrogen atmosphere; and sintering into the h-BN / VC machinable ceramic. The machinable ceramic obtained by the method has uniform h-BN phase distribution, controllable content, good machinable property, good mechanical properties and excellent thermal properties.

Description

technical field [0001] The invention relates to h-BN / VC machinable ceramics, belonging to the technical field of ceramic preparation. Background technique [0002] Ceramic materials have many excellent properties. However, due to the high hardness of ceramic materials, when preparing precision-sized ceramic parts, they can only be ground by diamond abrasive grinding wheels, and the manufacturing cost is very high. Therefore, people have been looking for a method that can not only meet the requirements of basic mechanical properties, but also obtain precision-sized ceramic parts by machining. In the 1990s, Japanese scholar Niihara and others adopted Si 3 N 4 Particle-coated h-BN prepared high-strength machinable ceramic parts, which opened up a new way for the preparation of high-performance machinable ceramic parts; in 2002, Li Yongli et al. 2 o 3 The analytical reagent CO(N 2 ) 2 and H 3 BO 3 Mixed at a molar ratio of 1:4, fully ground in a mortar, and high-purity ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C04B35/583C04B35/56C04B35/622
Inventor 唐竹兴
Owner SHANDONG UNIV OF TECH