欧美人妻精品一区二区三区99,中文字幕日韩精品内射,精品国产综合成人亚洲区,久久香蕉国产线熟妇人妻

Why should we study nanoceramic bonded carbide? As we all know, WC-Co carbide consists of hard phase (WC) and bonding phase (ferrous metal). In harsh environments, the bonding phase is more susceptible to corrosion and oxidation than the hard phase, which limits its application in some fields. Therefore, reducing the content of the bonding phase is considered to solve this problem. In addition, metal Co is an expensive material and has a certain impact on human health. It is necessary to reduce the application of Co in carbide from the perspective of reducing costs and human health.

Nanoceramic bonded phase WC-based carbide refers to a type of carbide product that does not contain or contains a small amount of metal bonding agent (<0.5% by mass fraction). It has unparalleled excellent wear resistance, corrosion resistance, excellent polishing, and oxidation resistance compared to traditional carbide.

nanoceramic bonded phase WC-based carbide is a combination of ceramic hardness and carbide toughness, and products have been launched abroad. With its excellent wear and corrosion resistance, it can be used to make sandblasting nozzles, electronic packaging materials, heavy-duty sliding seal wear-resistant parts, etc.. with its excellent cutting performance, it can be used as tool and drill materials, especially for processing titanium/titanium alloys, which greatly improves work efficiency. and with its oxidation resistance and excellent polishing, it can be used as mold and decorative materials.

nanoceramic bonded carbide's micro structure

Characteristics of nanoceramic bonded carbide:

1Phase structure and carbon content of nanoceramic bonded phase carbide carbide are very sensitive to carbon content. For traditional carbide containing bonding phases, there is a certain range of carbon content to maintain a normal phase structure. If this range is exceeded, brittle n-phase or free carbon will appear. In contrast, the suitable carbon content of nanoceramic bonded phase WC-based carbide is not fluctuating like WC-Co alloy but is a fixed value.

2Composition design and properties of nanoceramic bonded carbide

Nanoceramic bonded carbide, which combine mechanical and wear resistance properties perfectly, are one of the most widely used ceramic-based materials in engineering. However, in most ceramic-based materials, the existence of metal bonding phases not only makes these composite materials have excellent flexural toughness but also affects certain properties, which limits their use. In addition, the low melting point of metal Co also greatly limits the application of WC-Co cutting tools in high-speed machining, which is prone to serious adhesive wear and oxidation wear. Moreover, the poor corrosion resistance, high cost, and toxicity of Co also limit the mechanical industry application of WC-Co carbide. Therefore, partially or completely replacing the Co bonding phase can expand the application of carbide. In recent years, ceramic bonding phases have attracted widespread attention in the scientific community as a new type of Co substitute.

 

The specific study using Nanoceramics as Binder Phase in Hardmetal Alloys

The Research Institute of Shandong University in China selected nanoscale Al2O3, ZrO2, and MgO as the binder phase for WC hardmetal alloys. The microstructure and mechanical properties of the hardmetal alloys were compared, and the toughening mechanism of the nanoceramic oxides was explored. The related paper, titled “Nano-ceramic replacing cobalt in cemented carbide as binder phase: Is it feasible?”, was published in the Journal of Alloys and Compounds.

Paper link:

https://linkinghub.elsevier.com/retrieve/pii/S0925838821043784

 

What is nanoceramic bonded carbide? 1

 

 

 

 

4Mechanism of Ceramic Binders Improving Toughness of carbide?Materials

What is nanoceramic bonded carbide? 2

fig.1 TEM micrographs of nanoceramic bonded carbide: (a) dislocations in WC-6Al2O3, (b) dislocations in WC-6ZrO2, (c) dislocations in WC-6MgO, and (d) intragranular and intergranular microstructures of WC-6ZrO2.

After sintering, the WC grains retained their initial grain size, and the second phase significantly suppressed the grain growth of the WC matrix by limiting grain boundary migration. Dislocations were observed in all three nanoceramic bonded carbide materials, which enhanced the tolerance of the carbide. Additionally, it was found that some nanoscale ZrO2 grains were distributed along the WC grain boundaries, while more ZrO2 nanograins were distributed within the WC grains, forming so-called intragranular nanostructures. Compared with the ceramic binder phase at the WC grain boundaries, the ceramics inside the WC grains were smaller in size.

What is nanoceramic bonded carbide? 3

fig.2 The toughening mechanism of WC-6Al2O3

What is nanoceramic bonded carbide? 4

fig.3 The toughening mechanism of WC-6ZrO2

What is nanoceramic bonded carbide? 5

fig.4 The toughening mechanism of WC-6AMgO

During the high-temperature sintering and cooling process, residual tensile stresses are generated around the ceramic binder phase due to differences in thermal expansion coefficient, which is favorable for crack deflection when the crack reaches the stress field. When an external load is applied to the nano-ceramic binder material, the difference in elastic modulus causes a redistribution of microscopic stress, thereby increasing the material’s toughness. All three nanoceramic bonded carbide materials exhibit crack bridging, effectively reducing crack propagation energy. Non-branching cracks were also found in the carbide, greatly increasing the energy consumption of the main crack propagation and effectively slowing down crack propagation.

What is nanoceramic bonded carbide? 6

fig.5 XRD spectra of the polished surface and fractured surface of the WC-6ZrO2 specimen

During the fracture process of WC-ZrO2 carbide, when external stress is applied to the carbide, stress concentration occurs near the crack tip, promoting the transformation of t-ZrO2 to monoclinic m-ZrO2. This transformation significantly impedes the crack propagation by enhancing stress relaxation near the crack tip. In addition, the volume expansion caused by phase transformation compresses the surrounding matrix, which is conducive to crack closure. Furthermore, surface phase transformation can generate compressive stress, greatly increasing the toughness of the material.

Conclusione

In summary, compared with traditional WC-Co carbide, nanoceramic bonded carbide exhibit a better combination of fracture toughness and hardness. Compared with micro-ceramic bonded? carbide, the hardness and fracture toughness of nano-ceramic bonded phase carbide are simultaneously enhanced. This excellent hardness of nano-ceramic bonded phase carbide is crucial for high-speed machining applications and is expected to become a candidate material for high-speed machining tools.

Lascia un commento

Il tuo indirizzo email non sarà pubblicato. I campi obbligatori sono contrassegnati *

老司机精品免费在线视频| 国产精品视频一区二区三区八戒| 成人av大全免费一区二区三区| 最新日本一区二区三区免费看| 久久久久久久久中文字幕| 美女被大屌操大骚逼| 日韩成人伦理片在线观看| 公交车上被后入搞逼漫画| 欧美一区二区三区身体| 欲色欲香天天网综合久久| 三级无码日B视频| 骚片视频在线观看| 国产一区二区三区精品片| 美女荒郊野外找男人靠逼| 精品v欧洲高清欧美| 美女大鸡操很多水在线看| 东京热无码AV一区二区三区| 中文字幕人妻一区二区三区人妻| 国精品午夜福利视频导航| 我要操死你逼视频| 丁香婷婷亚洲六月综合色| 被几个大屌老外轮操| 亚洲国产区男人本色| 色哟哟精品视频一区二区| 在线免费观看一区二区三区| 玖玖资源站无码专区| 欧美精品第15页| 99久久精品国产一区二区成人了| 小穴抽插流水视频| 公交车上被后入搞逼漫画| 日韩有码一区二区三区在线观看| 男人操女人黄片黄色| 操女人大逼视频下载| 三上悠亚精品一区二区久久| 又色又爽又黄的吃奶Av| 大鸡扒干美女BB直流水| 亚洲av 又黄又爽十大| 区国产精品搜索视频| 咪咪爱一级特黄大片| 大鸡巴干浪穴视频| 农村胖肥胖女人操逼视频|