Papers by Keyword: Titanium Carbonitride

Abstract: In the present study austempered ductile irons (ADI) with lower bainitic structure are investigated. Nanosized particles (50nm) of titanium carbonitride + titanium nitride TiCN+TiN and titanium nitride TiN are added to the casting volume. The samples microstructure is studied by optical metallography and X-Ray analysis. The influence of the nanosized additives on the kinetics of the bainitic transformation and on the morphology of the bainitic structure is investigated. The abrasive wear testing, hardness measurements and impact strength are carried out. It is established that the presence of nanoadditives in the bainitic cast irons leads to the changes in their microstructure which increases their mechanical characteristics and abrasive wear resistance. The studied nanocomposite materials expand the potential for new ADI applications in the industry.

Abstract: The paper describes briefly the historical development and presents in more detail solid-state properties such as hardness, heat conductivity, thermal expansion and mechanical properties of titanium carbonitride Ti (C,N), the basis of the hard phase of cermets. The metallurgy of Ti (C,N)-based cermets with respect to microstructure formation during sintering and the impact on properties are presented in more detail. The various influences such as W and/or Mo content, Mo/W ratio, C content and C/N ratio, binder phase content and binder phase composition (Co/Ni), sintering time, dwell time, alloy state of powders and grain size were critically evaluated and are presented in form of fracture toughness vs. hardness graphs. A table gives a reference list on the study of these influences. TRS data on cermets were collected and summarised in a separate table, too. The focus is put on grades which have the potential of being fabricated soon in industrial processes for production of cermet tools. Application examples for metal cutting, sawing and chip bonding are presented. In two final sections recent modifications and achievements such as graded microstructures, multicomponent binder, and hybrid microstructures are also briefly presented together with an outlook on the future potential of cermet applications.

Abstract: A wear-resistant composite coating process with electroslag surfacing using a current-supplying solidification mould was developed. The structure and properties of coatings from flux-cored wire deposited alloys with refractory micro-particles of titanium diboride, TiB₂, and nano-sized particles of titanium carbonitride, TiCN, were studied. Special features of the elasto-plastic deformation of composite alloys’constituents were studied with sclerometry.

Abstract: Titanium carbonitride (TiCN) nanocrystaline powders were syntheiszed by reactive ball milling of titanium, graphite and urea. GN-2 ball milling was used and the rotation speed was 600rpm. The ratio of ball to material was 30:1, the milling time was from 10 hours to 50 hours. The powders milled for different time were analyzed by X-ray diffraction. The results show that TiCN powders can be synthesized by milling 10 hours, although some raw materials remained. After milled for 50 hours, the raw materials can reactive completely to form TiCN and the grain size of the TiCN powder was about 7 nm.

Abstract: HREM study on Ti-carbonitride particles in Ti-microalloyed steels has been carried out. It shows that many tiny Ti-carbonitride precipitates formed on nitride, sulfide or oxide particles. These carbonitrides possess twin relationship or have continuous interface with the particles existed already. The results imply that the twinning and epitaxial growth may be the important mechanisms for Ti-carbonitride formation in the steels. These nucleation mechanisms can highly lower the interfacial energy of new precipitates, resulting in the nucleation rate greatly increased. Therefore, the mechanical properties of the Ti-microalloyed steels are effectively improved.

Abstract: The carbonitriding treatment of deep reduced slag obtained in the smelting process of the non blast furnace with the vanadic titanomagnetite from PanZhiHua were carried out in a high temperature carbolic pipe furnace with nitrogen gas in order to obtain Ti(C,N). The results are found: there are a few of Ti (C, N) presented in the carbonitriding reaction production with theoretical amount of carbon at 1400°C; the content of Ti (C, N) increases with temperature; the carbonitriding reaction tends to finish at 1500°C; the average size of Ti(C,N) particles are 7.8452μm and the maximum is 21μm above 1600°C; the content of N in the Ti (C, N) decrease with temperature below 1400°C and that of N increase and the change of C content is opposite above 1400°C; To increase appropriately carbon amount can promoto the carbonitride reaction which is benefit for the formation and grow of the Ti (C, N); when the amount of carbon beyond the theoretical value, the maximum and average size of grains obtained is smaller. It shows that the bigger Ti(C,N) grains can be obtained and the high temperature is very important for the carbonitride treatment of the deep reduced slag to obtain Ti (C, N).

Abstract: TiCN matrix cermets were prepared by using traditional sintering and microwave sintering. The effect of sintering methods, sintering temperature and protective atmosphere to the densification process of as prepared material were discussed. The results show that microwave sintering can short the sintering time than the traditional sintering, but it need higher temperature to obtain approximate density. At 1500°C,holding 5min, vacuum microwave sintering can gain relative density of 99.5%. The relative density of TiCN matrix cermets under argon shield is lower than vacuum microwave sintering, and the microscopic particles is more small, but the uniformity of pore is reduced. Microwave sintering can greatly reduce energy consumption.

Abstract: Low carbon-manganese wrought steels with addition of Ti-Al-N have been treated in order to obtain acicular ferrite structure. The microstructure of fine acicular ferrite nucleated intragranularly on Ti(C,N)+AlN and Ti(C,N)+AlN+MeS inclusions has showed high strength and toughness at low temperatures.

Abstract: Nanoparticles of TiC and TiCN were synthesized by a magnesium thermal reduction process. The process was performed in the sequence of (1) the transfer of TiCl4+C2Cl4 solutions into a liquefied magnesium protected with Ar, (2) the magnesium reduction of metal chlorides, (3) the formation of a titanium carbide by the reaction of Ti and C atoms released by the magnesium reduction, and finally (4) the vacuum separation of the residual liquid Mg and MgCl2. Titanium carbonitride could be synthesized by maintaining the reaction chamber in nitrogen atmosphere. The average particle size of both TiC and TiCN synthesized was about 80 nm each. The composition of the TiC nanoparticles was approximately TiC0.95 with 0.9 wt % free carbon whereas that of the TiCN nanoparticles was TiC0.46~0.53N0.46~0.51 with 0.1 wt % free carbon.

Abstract: In present works, the low cost TiO2 powders were partially introduced to raw mixture as playing roles of both reactant and dilution. The experimental results showed that increasing the ratio of TiO2 to titanium powders up to 70wt%, the combustion synthesis reaction could still proceed by self-sustained mode. Single phase of TiNxC1-x with ultra fine particle size could be prepared by using TiO2 as dilution. Influences of TiO2 addition on phase formation and microstructure of product were also investigated. It was found that the combustion temperature and as-synthesized TiNxC1-x particle size decreased as increasing the amount of TiO2 addition.