Experimental Application of Rare Earth Carbide

[Abstract] cobalt in tungsten and tungsten carbide titanium cobalt rare earth elements can add a small amount of carbide bending strength, toughness, wear resistance, impact resistance and red hardness are greatly improved tool life of the alloy increased significantly. Looking at earth carbide products in the process of manufacture and use of the effect of its analysis.

[Keywords:] physical and mechanical properties of rare earth alloy

Summary
Rare Earth Elements in metallurgy, machinery, petrochemicals, energy, light Industry, environmental protection, agriculture and electronics Industry applications is very broad, and its role attracting much attention, generally considered as "elements of the future." Metal materials, rare earth has been People send in the hope of improving the performance of modified hardening material. home and abroad, Rare Earth made very early, has been successfully applied to the domestic steel Industry, and achieved good results. The application is also in the carbide achieved great results, there are many reports in this regard.

REE is the periodic table of the third family of the sixth cycle of lanthanide and yttrium and scandium are similar to a total of seventeen elements. REE chemical properties is very lively, with oxygen, a strong affinity for sulfur, its compounds are very stability. noted in the data reported in the carbide in the small amount of rare earth oxide added, even without the decline in strength and hardness of cemented carbide, but lead to a decline in the cutting performance of cemented carbide, such as its uneven distribution in the body, have segregation, but also can be a mixed oxide, rare earth oxides in the alloy it is basically not to the application. can be seen, adding mode and mixed-effects directly related to the physical and mechanical properties of cemented carbide is good or bad, usually adding trace elements a single quality, oxides and solid solution (intermediate alloy) in the form to join, adding master alloys in the form method is widely used in black and non-ferrous metal alloy smelting, and rare earth metals and oxides carbide is usually in the form to join. oxide form added desirable, and rare earth metals in the powder state to join the system difficult to access and add technology to a certain extent, limit the application. currently used is a mixture of rare earth cobalt powder as additive, with good results.


An experiment and application results
(1) Mixed powder ratio: YT5Re (fine WC, TiC-WC and Co supersaturated solid solution of cobalt and rare earth additives, Ce addition is 0.5% cobalt content), preparation of WC-5TiC-10Co-Re Carbide experimental material powder.

(2) Ball: The wet (ethanol medium, the ball ratio of 3:1), vacuum drying.

(3) other; joined forming agent compaction. A standard 5mm �� 5mm �� 30mm bending specimens and rough blade. And then by the (1470-1530) �� 40min vacuum sintering.

(4) Test results:
Ts �� 1420 �� 1450 �� 1470 ��
HRA89.589.9 89.7
��bb (Mpa) 168019101850
��13.013.0 13.1
(5) the use of comparative results (98W-Fe-Ni-Co cutting bar):
Compared with conventional YT5: 3 times increased wear resistance, chipping down 2 times, 3.2 times life. (During the test production statistics) Links to Research Papers Download Result Analysis Center http://www.hi138.com 2
These results show that the addition of rare earth Ce in the alloy can effectively improve the tensile strength, abrasion resistance, impact resistance and other properties, thereby enhancing the life of the alloy.

Organizational structure determines alloys, from the Ce addition on analytical aspects of organizational impact.

(1) Ce in the alloy and role in the distribution of
The metallographic observation, Ce and Co solid solution, resulting in a Co The lattice distortion, thus reinforcing the binder. In addition, the harmful impurities and raw materials into sulfur and oxygen combine to form compounds, thus purifying the phase interface. because the sulfur, the presence of oxygen hinders the phase binder phase and hard, hard contact phase and hard phase connection, reducing the bond strength. reduction of sulfur, oxygen hazards, must improve the bonding phase and hard phase WC wetting effect. Also has information reported, rare earth phase can dissolve some of the other harmful impurities, also reduced the hazards of harmful impurities in the alloy. This shows that rare earth metals in the alloy to purify the binding phase and grain surface increase the bond between the wetting phase and the grain and reduce the role of harmful impurities. It is reported that the addition of rare earth elements also help to dissolve the binding phase W, and played a "dispersion strengthening" effect, therefore, bending strength of the rare earth alloy greatly improved.

(2) rare earth Ce on the role of sintering in vacuum
From the experimental results show that the sintering process at all temperatures, the alloy is fine and uniform grain size, no significant growth of the phenomenon, that rare earth metal alloy can effectively suppress grain growth, stability, sintering, to obtain good performance alloy products.

(3) Optimization of alloy metals the role of the organizational structure
Seen from the metal microstructure pattern, up and down there at 400 �� crystal changes with the different elements, namely, high temperature stability of the @-Co (fcc structure) solid solution into a low-temperature phase ��-Co (hcp structure), @ is ten cubic system two slip systems, which was retrospective. �� is the hexagonal lattice with three slip systems were brittle. RE added to the @-Co Co relative to the main phase, stable fcc crystal structure, help to improve Co, retrospective. This has been chipping tool applications have been fully proved effective, the observation of the microstructure can be seen, is significantly improved impact resistance.


3 Conclusion
(1) rare earth elements can improve the physical and mechanical properties of cemented carbide and the effect is obvious.

(2) rare earth elements in cemented carbide alloys can be optimized organizational structure and purification of the phase interface.

(3) rare earth alloy can be refined grains, stable sintering process, reduce the sintering temperature sensitivity.

These are the performance of the macro and micro superficial analysis of the crystal structure of rare earth on the role and influence of carbide, the role of rare earth elements in cemented carbide may not be so simple, yet to be further studied and discussed.


References
[1] You Liping. Rare Earths, 1990 (8) 4.

[2] He from the hearing. Rare Earths, 1994 (12) 3.

[3], Metallurgical Industry Press. Carbide production. Links http://www.hi138.com Research Papers Download