Papers by Keyword: Transverse Rupture Strength

Abstract: Two different ruthenium content (0.5%, 1.0%) of WC - (W, Ti, Ta) C - Co cemented carbide were prepared by conventional cemented carbide production process. The results showed that adding ruthenium powder can improve the microstructure of alloy compared with excluding ruthenium carbide. The microstructure of alloy with ruthenium addition had uniform structure with less coarse grain.The addition of ruthenium could obviously promote the transverse rupture strength of WC - (W, Ti, Ta) C-Co cemented carbide, and when the adding amount was 1.0%, transverse rupture strength increased by 30%. The addition of ruthenium slightly increased the hardness of the alloy. The results of Scanning electron microscopy and spectrum analysis showed that ruthenium mainly existed in the bonding phase Co. The cutting test showed that the alloy with Ru had better wear resistance.

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: Carbon–copper composites are attractive materials used for electrical applications, such as brushes for engines and generators, slip rings, switches, relays, lugs, contactor and current collector. Various methods can be used to prepare Carbon-copper composite, such as infiltration, sintering, cold pressing, hot pressing or isostatic pressing. However, powder metallurgy route is seen to be most favorable due to its possibility of producing uniform microstructure and excellent net shape product. In this work, carbon-copper composite is prepared using powder metallurgy route with warm compaction process. The compaction pressure (A), compaction temperature (B), post baking temperature (C) and compaction time (D) were optimized by Taguchi method. Hardness and transverse rupture strength (TRS) were used to assess the effect of warm compaction process. The experimental design is according to the L9 (3⁴) orthogonal array. Signal to noise and analysis of variance (ANOVA) are employed to analyze the effect of warm compaction parameters. It is found that the best parameters and their levels are A3B2C3D2 for the main effect of hardness and the best parameters and their levels for TRS is A3B2C3D1. It is also notified that optimized parameters of A3, B2 and C3 are identical for hardness and TRS. However, for parameter D, the best level for hardness is D2 and for TRS is D1. The ANOVA analysis proved that compaction temperature parameter is significant to hardness and TRS value whereas the others parameters are not significant.

Abstract: The effect of VC and Cr₃C₂ grain growth inhibitors on mechanical properties of the WC-Ni-ZrO₂ composites are studied in the present work. The microstructural features responsible for a change in mechanical properties are analysed. Addition of both VC and Cr₃C₂ results in increase in hardness of the WC-based system, but consequently in decrease in fracture toughness. The transformation toughening effect of ZrO₂ is not effective for the loading conditions applied in this study.

Abstract: The present work is a study on the argon gas pressure effects of Sinter/HIP sintering on microstructure and strength of different grades of TiC-NiMo cermets. Titanium carbide in the composition of different grades of TiC-NiMo cermets was ranged from 40 to 80 wt.% and the ratio of nickel to molybdenum in the initial powder composition was 1:1, 2:1 and 4:1 respectively. On the sintered alloys, the main strength characteristic, transverse rupture strength (TRS) and erosion wear resistance were measured. Furthermore, the microstructure parameters of some alloys were measured and the pressure effect on pore elimination was evaluated. All the results were compared with common, vacuum sintered alloys. The TRS values of TiC-NiMo cermets could be considerably improved by using Sinter/HIP technique, for high-carbide fraction alloys and for alloys sintered at elevated temperatures. The results provide new possible application fields for Sinter/HIP-ed TiC cermet materials to areas where, in addition to wear performance, higher strength properties are demanded.

Abstract: For effective rough milling, an optimized criterion is required to select the feedrate. In this study, a method to obtain the most appropriate reference cutting force for rough milling was developed. The reference cutting force was determined by considering the transverse rupture strength of the tool material and the area of the rupture surface. A finite element method analysis was performed to accurately calculate the area of the rupture surface. Using the analyzed results, the effect of various cutting parameters on the chipping phenomenon was determined. The calculation method for the reference cutting force considered the area of the rupture surface, the effect of the rake angle, and the axial depth of cut. The experimental results clearly show that the reference cutting force obtained from the proposed method met the desired constraints.

Abstract: Mechanically-alloyed NiAl powder was sintered by Spark-Plasma Sintering (SPS) process. Densification behavior and mechanical property were determined. Above 97% relative density was obtained after sintering at 1150oC for 5min. Crystallite size determined by the Scherrer method was approximately 80 nm. TEM observation revealed a relative larger crystallite size. X-ray diffraction analysis showed that the sintered bodies were composed mainly of NiAl phase together with Ni3Al phase. Sintered NiAl body showed an average Vicker’s hardness of 555Hv, transverse-rupture strength of 1393MPa, 4-point-bending strength of 1100MPa, and fracture toughness of 19.9MPa m-1/2