Ahmet Yönetken

Characterization and brazing of sintered Ni-Al-Co powder mixtures containing intermetallics

Abstract Powder metallurgy is a progressive branch of engineering that enables engineers to fabricate difficult-to-make parts and materials that are used in many industrial areas. Joining this class of materials is a difficult task due to their intrinsic limitations, such as porosity and thermal properties. In this study, varying ratios of Co powder additions to Nix+Aly powder mixture were made prior to sintering at 600°C. The sintered samples were brazed in both microwave and traditional tube furnaces by placing brazing filler alloy between the sintered specimens without added weight at 950°C for 15 min. Scanning electron microscopy and X-ray diffraction techniques were employed to characterize the brazed samples and the joints. Shear strength and hardness of brazed joints were also determined.

Manufacturing microwaved hardmetal composites

Nickel matrix composites reinforced with tungsten carbide have been fabricated by Turkish researchers using microwave sintering at various temperatures. They say microwave sintering of cobalt and electroless nickel plated tungsten carbide powders is a promising technique to produce ceramic-reinforced nickel composites…

MW sintering ‘the economic way’ to ceramic reinforced nickel aluminide composites

Hardmetals are tough when it comes to cutting metal, but their virtues can be enhanced by reinforcement with ceramic particles, say Turkish researchers. Microwave sintering provides a lower energy alternative to normal processing…

Investigation Efficiency and Microcontroller-Based Energy Flow Control for Wind-Solar-Fuel Cell Hybrid Energy Generation System with Battery Storage:

In this proposal, microcontroller-based energy flow control was designed in order to effectively and efficiently enable the use of energy sources in a hybrid energy generation system including wind, solar, and hydrogen energy. It was assumed that the hybrid energy generation system is dynamic during the design of the microcontroller-based energy flow control. A wind–solar energy generation system was determined as the base load power plant. Depending on the demand, the battery group and fuel cell were activated effectively. If an energy surplus occurred, it was stored in battery groups and transformed into hydrogen energy via a hydrogen generator simultaneously. In addition to providing energy sustainability, a constant active status of the energy storage group was prevented and the physical life of the group was prolonged by means of the microcontroller-based control system. If consumer demand could not be met by the main energy sources including wind and solar energy, the battery groups and fuel cell were activated and provided the energy sustainability. After a certain level of charge was reached in the battery group, it was deactivated via the control system in order to prevent unnecessary use of energy. By means of the microcontroller-based control system, the usage of energy generated with the hybrid energy generation system was analysed according to its efficiency.

Kondansatör Deşarjli Saplama Kaynağı Kaynak Voltunun Aa6082 Alüminyum Alaşımında Birleşmeye Etkisi

Bu calismada O4 mm standart aluminyum saplamalar kullanilarak 6082 Alasimi farkli volt ayarlarinda kaynaklanmistir. Dusuk ve yuksek volt degerlerinde yapilan saplamalarda birlesme zayif ve yada hic saglanamamistir. Fakat saplama capina uygun secilen volt degerlerinde (150 V ve 160 V) ise kaynak bolgesinde kopma olmadan yapilan baglanti saplamalari kendi ekseninde doksan derece egilerek test edilmistir.

Production and wear property of electroless Ni-plated B4C-AstaloyCr-M composites

Abstract Nickel (Ni) matrix reinforced with boron carbide (B4C) has been produced by conventional furnace sintering at various temperatures. A uniform Ni layer on B4C powders was deposited prior to sintering using electroless plating technique, allowing close surface contact between particles. A composite consisting of quaternary additions, a ceramic phase, B4C, within a matrix of Ni and AstaloyCr-M powders has been prepared at a temperature range of 1000°C–1200°C under Ar shroud. X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM) study, compressive testing, and hardness measurements were employed to characterize the properties of the composite. Experimental results showed that the best properties as compressive strength σmax and hardness (HB) were obtained at 1150°C. Wear resistance was relatively higher than cast iron.

Fabrication of electroless Ni plated Fe-TiC metal matrix composites

Abstract Ni-Fe metal matrix composites reinforced with TiC have been fabricated by tube furnace sintering at various temperatures. A uniform nickel layer on TiC and Fe powders was deposited using electroless plating technique prior to sintering, allowing closer surface contact than can be achieved using conventional methods, such as mechanical alloying. The reactivity between TiC and Fe powders, to form carbides of Fe, is controlled through Ni layer existing on the starting powders. A composite consisting of quaternary additions, a ceramic phase, TiC, within a matrix of FeNi, has been prepared at the temperature range 1000–1400°C under argon shroud. X-ray diffraction, scanning electron microscope (SEM), compressive testing and hardness measurements were employed to characterize the properties of the specimens. Experimental results carried out at 1200°C suggest that the best properties, such as maximum compression strength (σmax) and hardness (HB), were obtained at 1200°C and the tube sintering of electroless Ni plated TiC and Fe powders, is a promising technique to produce ceramic reinforced Ni-Fe composites.

How composite formation can improve NiAl intermetallics

Intermetallics are among advanced technology materials that have outstanding mechanical and physical properties for high temperature applications. Turkish research has looked more closely at the addition of cobalt to NiAl intermetallics to form composites…

Diffusion bonding of electroless Ni plated WC composite to Cu and AISI 316 stainless steel

In this study, a composite containing WC (Tungsten Carbide) and Ni was produced by two different processing routes. Electroless Ni coated WC powders were consolidated and sintered at 1200 °C. Diffusion bonding couples of WC(Ni)-electrolytic Cu, WC(Ni)-AISI 316 stainless steel and WC(Ni)-WC(Ni) were manufactured by using a preloaded compression system under Ar atmosphere. Diffusion bonding was carried out at varying bonding temperatures; 750 °C for (WC)Ni-Cu diffusion couple and 1200 °C for (WC)Ni-(WC)Ni and (WC)Ni-AISI 316 stainless steel diffusion couples. Standard metallographic techniques, Scanning Electron Microscopy and a shear test were employed to characterize the microstructure of bondline and mechanical properties of each diffusion couple, respectively.