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2 Journal of Achievements in Materials and Manufacturing Engineering

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The comparison of the sintering methods for diamond cutting tools

Bulut B., Tazegul O., Baydogan M., Kayali E. S.

Journal of Achievements in Materials and Manufacturing Engineering

2016

Vol. 76, nr 1

30--35

Purpose: Aim of this study is to compare mechanical, physical, microstructural properties of diamond cutting tools (DCTs) made of Co-Ni-Cu-Sn matrix, produced by Spark Plasma Sintering (SPS) and Conventional Sintering (CS) methods. The main reason for this research is choosing the most convenient and economically manufacturing method for diamond cutting tools. Design/methodology/approach: Aim of this study is to compare mechanical, physical, microstructural properties of diamond cutting tools (DCTs) made of Co-Ni-Cu-Sn matrix, produced by Spark Plasma Sintering (SPS) and Conventional Sintering (CS) methods. The main reason for this research is choosing the most convenient and economically manufacturing method for diamond cutting tools. Findings: The results showed that, the density values of the samples which are produced two different sintering methods are similar. However, the mechanical and microstructure properties of the samples which are produced by SPS method are decent. The robust mechanical properties were obtained at SPS method than CS method. Practical implications: Powder metallurgy is the most common method because of forming new diamond grains due to wearing of matrix. In powder metallurgy, Conventional Sintering (CS) and Spark Plasma Sintering (SPS) are used at DCTs production prevalently. SPS is a short and effective way to produce diamond tools but costs are higher and production capacity is lower than conventional sintering method. Originality/value: This paper demonstrates that the sintering methods can effect the cutting performances of the DCTs. The samples which are produced with CS method had elevated cutting performance on-site field tests.

Effects of deformation rates on mechanical properties of PP/SEBS blends

Balkan O., Demirer H., Kayali E. S.

Journal of Achievements in Materials and Manufacturing Engineering

2011

Vol. 47, nr 1

26--33

Purpose: The goal of this study is to examine effects of tensile deformation rates ( e) on tensile properties of polypropylene/poly(styrene-b-ethylene-co-butylene-b-styrene) copolymer (PP/SEBS) blends and to determine suitable S for accurate and reliable evaluation of mechanical properties of the blends in accordance with the results of Izod impact tests. Design/methodology/approach: PP/SEBS blends containing ϕ_e= 0, 2.5, 5 and 10 volume % of SEBS thermoplastic elastomer were compounded using a twin-screw extruder, and then moulded with an injection moulding machine. Morphology of PP/SEBS blends were analysed by scanning electron microscopy (SEM). Mechanical properties of the blends were investigated tensile and Izod impact tests. Tensile deformation rates έ=1.67 ms^-1 and έ₂=16.67 ms^-1 were used to determine ultimate tensile properties. Findings: Morphological analyses revealed that SEBS elastomer particles were well-dispersed throughout PP matrix in irregular forms with a narrow size distribution and evidenced a two-phase system formation. At low deformation rate(έ), PP and PP/SEBS blends did not fail during tensile tests despite maximum tensile deformation, ε_max = 600%; therefore, tensile toughness (U_T), stress and strain values at break point (σ_b and ε_b) of the blends were not determined. However, at high deformation rate ( έ₂), all specimens tested in this study failed; a slight decrease in ob of the blends with SEBS elastomer was associated with a significant increase in ε_b and U_T. Strain-rate-sensitivity of PP/SEBS blends was promoted with SEBS elastomer. Research limitations/implications: Mechanical properties determined through high-velocity tests are beyond the scope of this study. Practical implications: έ of tensile testing machines is readily adjustable, while ε_max of tensile testing machines is limited. Consequently, in order to evaluate reliably mechanical properties of ductile materials like PP/SEBS blends, e must be so high that ductile materials can fail during tensile tests. Originality/value: Tensile testing at high strain rate έ₂ was concluded to be more suitable for evaluation of mechanical properties of PP/SEBS blends than that of at low strain rate έ₁.