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Preparation method of h-BN / HfC machinable ceramic

A ceramic and h-bn technology, applied in the field of h-BN/HfC machinable ceramics, can solve the problems of low bending strength and achieve high strength, uniform microstructure and high overall reliability

Inactive Publication Date: 2014-06-18
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 the HfC ceramic powder with a particle size of 0.1 μm to a 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 HfC powder, nitriding the above-mentioned coated HfC powder at a temperature of 600°C for 30 minutes in a nitrogen atmosphere to obtain h-BN coated HfC ceramic powder, and h-BN coated HfC ceramic powder at a pressure of 100MPa. The lower isostatic pressing is pressed into a ?60×10mm sheet-shaped body, and then hot-pressed at 1700°C×30 minutes under a nitrogen atmosphere at 5MPa. Fired into h-BN / HfC machinable ceramics.

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

Embodiment 2

[0016] The first step: uniformly mix boric acid: urea in 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 HfC 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 HfC powder, nitriding the above coated HfC powder at a temperature of 800°C×45 minutes in a nitrogen atmosphere to obtain h-BN coated HfC ceramic powder, and h-BN coated HfC ceramic powder under a pressure of 150MPa. Press isostatically into a ?60×15mm sheet green body, and then hot-press 50MPa under a nitrogen atmosphere at 1800°C×105 minutes. Fire into h-BN / HfC 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 / HfC machinable ...

Embodiment 3

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

[0021] Step 2: Add 40% of the HfC ceramic powder with a particle size of 2 μm into a 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 HfC powder, nitriding the above coated HfC powder at a temperature of 1000°C×60 minutes in a nitrogen atmosphere to obtain h-BN coated HfC ceramic powder, and h-BN coated HfC ceramic powder under a pressure of 200MPa. Press isostatically into a ?60×20mm sheet green body, and then hot press 100MPa under a nitrogen atmosphere at 1850°C×180 minutes. Fire into h-BN / HfC machinable ceramics.

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

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Abstract

A preparation method of an h-BN / HfC machinable ceramic. The method is characterized by subjecting an h-BN coated HfC ceramic powder to a cold isostatic pressing for forming, and sintering the ceramic by hot pressing to obtain an h-BN / HfC machinable ceramic. The method comprises steps of: mixing boric acid and urea with ethanol according to a proportion to prepare an esterification solution in a closed container; then adding the HfC ceramic powder into the esterification solution to prepare a ceramic slurry; preparing the ceramic slurry into a coated HfC powder by a spray granulation machine; nitridizing the coated HfC powder to obtain the h-BN coated HfC ceramic powder; pressing the h-BN coated HfC ceramic powder by isostatic pressure into a plate blank; subjecting the plate blank to hot pressing under nitrogen atmosphere; and sintering the plate blank into the h-BN / HfC machinable ceramic. The h-BN / HfC machinable ceramic prepared by the method provided by the invention has advantages of uniform h-BN phase distribution, controllable content, and good processing property, mechanical property and thermal property.

Description

technical field [0001] The invention relates to a h-BN / HfC machinable ceramic, which belongs 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-...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C04B35/56C04B35/628
Inventor 唐竹兴
Owner SHANDONG UNIV OF TECH