Apakah Tungsten Carbide?

What is cemented carbide? What are its characteristics?

Definition

cemented carbide is a composite material produced by powder metallurgy and composed of refractory metal compounds (hard phase) and bonding metals (bonding phase).

Features

High hardness and wear resistance;

High compressive strength (up to 6000mpa);

Good stability;

Brittle.

Kelebihan

compared with tool steel, cemented carbide has the following advantages:

Greatly improve the tool life, several times to dozens of times;

The cutting speed and labor efficiency are improved;

The accuracy and smoothness of the workpiece are improved.

Komposisi, struktur dan sifat karbida bersimen

Composition

the main components of cemented carbide are WC, CO and tic, and the secondary components are tin, Ni, Mo, TAC, NBC, VC, Cr3C2, etc. Among them, WC (including TIC) accounts for more than 80% and co accounts for less than 20%. The proportion of other components is very small.

Structure

the normal structure of tungsten cobalt alloy is the two-phase structure of WC phase and co phase. The former is also called hard phase or α Phase, the latter is adhesive phase or β Phase. There are two normal structures of tungsten titanium cobalt alloys, one is (Ti, w) c+co two-phase structure, and the other is (Ti, w) + wc+co three-phase structure.

Performance

The main performance indicators of cemented carbide include density, bending strength, hardness, coercive force, cobalt magnetism, etc. Density is the most basic index of cemented carbide quality, and it is the basis of other properties. Hardness and bending strength are the two main mechanical properties of cemented carbide, which directly affect the application effect of the alloy. These three properties basically determine the comprehensive quality of cemented carbide, which is not only the evaluation index of products leaving the factory, but also the index that users pay most attention to, and an important basis for the rational selection of cemented carbide.

Fungsi beberapa bahan yang biasa digunakan dalam bahan alat:

WC – wear resistant phase, the main component of tool material;

Co – ductile phase, with the increase of CO content, the strength and toughness of the alloy increase and the hardness decreases;

TiC – hard phase, with the increase of TiC content, the anti crater wear ability of the alloy increases, but the strength and toughness of the alloy decreases, and the brittleness of the alloy increases;

TAC, NBC – hard phase, which can significantly improve the high temperature performance and wear resistance of the alloy. The alloy with TAC and NBC has good versatility;

CRC, VC inhibitors, inhibit the growth of WC grains.

Classification of cemented carbide

According to different compositions, cemented carbide can be divided into five categories.

Tungsten carbide based cemented carbide

including WC Co, WC tic Co, WC TAC Co, WC tic tac (NBC) -co, etc. These alloys are mainly composed of WC.

Titanium carbide based or titanium carbonitride based cemented carbide

a kind of cemented carbide usually composed of tic or Ti (C, n) as the basic component and Ni Mo as the binder. Such as tic Mo Ni, tic WC TAC (NBC) -mo Ni, Ti (C, n) -mo Co Ni, etc.

Coating cemented carbide

deposit a layer of tic, tin, TiB2, ZrN, CrN, AI2O3, TiCN, B4C, SiC, BN, TiAIN, diamond and other substances on the alloy surface, so as to double the service performance of the tool.

Steel bonded cemented carbide

a kind of cemented carbide whose main component is steel and whose hard phase is tic or WC. Its remarkable feature is that it can be heat treated and machined. It is a kind of intermediate alloy between tool steel and cemented carbide.

Other cemented carbide

such as Cr3C2 based cemented carbide, which is composed of Cr3C2 as the main component and Ni or Ni-W as the binder. It is usually used as wear-resistant and corrosion-resistant parts.

Di samping itu, terdapat dua bahan alat penting. Satu ialah bahan seramik, termasuk alumina (tembikar putih), silikon nitrida dan seramik Theron (si3n4/al2o3). Yang lain ialah bahan superhard, berlian polihabluran (PCD) dan boron nitrida padu polihabluran PCBN.

Classification by purpose

Karbida bersimen mempunyai satu siri sifat yang sangat baik dan digunakan secara meluas. Dengan peredaran masa, penggunaannya semakin berkembang. Kegunaan utama adalah seperti berikut:

Alat pemotong

karbida bersimen boleh digunakan sebagai pelbagai alat pemotong. Penggunaan karbida bersimen bagi alat pemotong di China menyumbang kira-kira satu pertiga daripada jumlah keluaran karbida bersimen (kira-kira 3000 tan), di mana kira-kira 78% digunakan untuk alat kimpalan dan kira-kira 22% digunakan untuk alat boleh diindeks. Karbida bersimen yang digunakan untuk alat kawalan berangka hanya menyumbang kira-kira 20% daripada karbida bersimen yang digunakan untuk alat boleh diindeks. Di samping itu, terdapat alat pemotong seperti mata gerudi karbida bersimen integral, mata gergaji bulat kecil karbida bersimen kamiran, dan gerudi mikro karbida bersimen.

Alat perlombongan geologi

alat perlombongan geologi juga merupakan penggunaan utama karbida bersimen. Karbida bersimen untuk perlombongan di China menyumbang kira-kira 25% daripada jumlah pengeluaran karbida bersimen. Ia digunakan terutamanya untuk mata gerudi untuk penggerudian impak, bit untuk penerokaan geologi, gerudi bawah lubang untuk lombong dan medan minyak, gerudi penggelek, pemilih pemotong arang batu, gerudi hentaman untuk industri bahan binaan, dsb.

Acuan

karbida bersimen yang digunakan sebagai pelbagai acuan menyumbang kira-kira 8% daripada jumlah pengeluaran karbida bersimen, termasuk cetakan dawai, cetakan kepala sejuk, mati penyemperitan sejuk, mati penyemperitan panas, mati tempa panas, acuan membentuk, dan mandrel tiub lukisan, seperti long mandrel, mandrel sfera, mandrel terapung, dsb. dalam beberapa dekad kebelakangan ini, penggunaan pelbagai gulungan karbida bersimen yang digunakan untuk bahan dawai rolling telah meningkat dengan pesat, dan karbida bersimen yang digunakan untuk gulungan di China telah menyumbang 3% daripada jumlah pengeluaran karbida bersimen .

Bahagian struktur

terdapat banyak produk yang diperbuat daripada karbida bersimen untuk bahagian struktur, seperti cincin meterai berputar, piston pemampat, chuck pelarik, gelendong pengisar, jurnal galas, dll.

Pakai bahagian tahan

bahagian tahan haus yang diperbuat daripada karbida bersimen termasuk muncung, rel panduan, pelocok, bola, paku anti-gelincir tayar, plat penyodok salji, dsb.

Cavity for high pressure and high temperature resistance

the most important use is to produce top hammer, cylinder and other products for synthetic diamond. Cemented carbide for top hammer and cylinder has accounted for 9% of the total cemented carbide production in China.

Kegunaan lain

karbida bersimen digunakan lebih dan lebih meluas, dan telah berkembang dalam bidang sivil dalam beberapa tahun kebelakangan ini, seperti rantai jam tangan, kotak jam tangan, kepala zip bagasi gred tinggi, tanda dagangan karbida bersimen, dll.