Apa itu 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.

Keuntungan

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 semen karbida

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 zat yang umum 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.

Selain itu, ada dua bahan alat penting. Salah satunya adalah bahan keramik, antara lain alumina (gerabah putih), silikon nitrida dan keramik Theron (si3n4/al2o3). Yang lainnya adalah bahan superhard, berlian polikristalin (PCD) dan PCBN kubik boron nitrida polikristalin.

Classification by purpose

Semen karbida memiliki serangkaian sifat yang sangat baik dan banyak digunakan. Dengan berlalunya waktu, penggunaannya semakin berkembang. Kegunaan utamanya adalah sebagai berikut:

Alat pemotong

semen karbida dapat digunakan sebagai berbagai alat pemotong. Konsumsi karbida semen dari alat pemotong di Cina menyumbang sekitar sepertiga dari total output karbida semen (sekitar 3000 ton), di mana sekitar 78% digunakan untuk alat las dan sekitar 22% digunakan untuk alat yang dapat diindeks. Karbida semen yang digunakan untuk alat kontrol numerik hanya menyumbang sekitar 20% dari karbida semen yang digunakan untuk alat yang dapat diindeks. Selain itu, ada alat pemotong seperti mata bor karbida semen integral, mata gergaji bundar kecil karbida semen integral, dan bor mikro karbida semen.

Alat pertambangan geologi

alat pertambangan geologi juga merupakan penggunaan utama dari karbida disemen. Karbida semen untuk pertambangan di Cina menyumbang sekitar 25% dari total produksi karbida semen. Ini terutama digunakan untuk mata bor untuk pengeboran benturan, mata bor untuk eksplorasi geologi, bor lubang untuk tambang dan ladang minyak, bor rol, pick pemotong batubara, bor impak untuk industri bahan bangunan, dll.

Cetakan

karbida semen yang digunakan sebagai berbagai cetakan menyumbang sekitar 8% dari total produksi karbida semen, termasuk dies penarikan kawat, dies pos dingin, dies ekstrusi dingin, dies ekstrusi panas, dies tempa panas, dies pembentuk, dan mandrel tabung gambar, seperti mandrel, mandrel bulat, mandrel apung, dll. Dalam beberapa dekade terakhir, konsumsi berbagai gulungan karbida semen yang digunakan untuk bahan kawat rol telah meningkat pesat, dan karbida semen yang digunakan untuk gulungan di Cina telah menyumbang 3% dari total produksi karbida semen .

Bagian struktural

ada banyak produk yang terbuat dari karbida semen untuk bagian struktural, seperti cincin segel berputar, piston kompresor, chuck bubut, spindel gerinda, jurnal bantalan, dll.

Bagian tahan aus

bagian tahan aus yang terbuat dari karbida semen termasuk nozel, rel pemandu, plunger, bola, paku anti selip ban, pelat sekop salju, dll.

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.

Penggunaan lainnya

karbida semen digunakan lebih dan lebih luas, dan telah berkembang di bidang sipil dalam beberapa tahun terakhir, seperti rantai arloji, kotak arloji, kepala ritsleting bagasi bermutu tinggi, merek dagang karbida semen, dll.