scholarly journals Investigation of the effect of addition of boron nitride on microstructure and mechanical properties of cast iron brake materials used in railway vehicles

Author(s):  
Harun Cug ◽  
Khangardash Asgarov ◽  
Gülcan Tigci ◽  
Mustafa Dursunlar

In this study, characterization of cast iron break shoes used in locomotives and the effect of BN addition and BN addition on microstructure and mechanical properties by using powder metallurgy (PM) method by adhering to the chemical composition of cast iron break shoes were investigated. In this context, cast iron sabers were chemically analyzed and all elements were supplied in powder form, and then BN added powder compositions were produced by cold and hot pressing technique. A total of 4 different compositions were created without BN, with 0.25, 0.5 and 1 % BN addition. Cold pressing was made in a steel mold with a diameter of 10 mm under 700 MPa pressure under room conditions. Hot pressing was carried out in a graphite mold with a diameter of 15 mm in an argon atmosphere under a pressure of 45 MPa at a temperature of 900 °C. Then the cold and hot pressed samples were sintered at 1 200 °C for 2 hours in argon atmosphere. Density measurement of the produced compositions, microstructure examination, micro hardness measurement were made. Generally, in density measurements, the densities of the samples subjected to hot pressing were higher than the cold pressing process. The hardness value decreased in parallel with the addition of BN. Keywords: Brake shoe; powder metallurgy; microstructure; mechanical properties

2017 ◽  
Vol 49 (3) ◽  
pp. 225-234
Author(s):  
Ertuğrul Çelık ◽  
Alı Aslan

Cu-Ni-MX1480 powder compound were prepared at six different alloy ratios and cold pressed with a pressure of 300 MPa. Then 12 samples were obtained by hot pressing at 700 ?C with 20 MPa pressure and at 800?C with 30 MPa pressure for 4 minutes in a vacuum atmosphere hot pressing machine. Porosity ratios of samples were calculated by the different between theoretical density and measured density of samples. Effect of porosity on microstructure and mechanical properties were investigated by performing SEM, XRD, hardness measurements and TRS tests. It was observed that as a result of increased hot pressing parameters and increased Cu ratio, porosity ratio was decreased and better mechanical properties achieved.


Author(s):  
Lazhar Baroura ◽  
Abdelyamine Boukhobza ◽  
Akila Derardja ◽  
Kamel Fedaoui

In the present work, Fe-Cu based alloys with different compositions have been obtained by using Powder metallurgy (PM). These alloys were created with the purpose of increasing mechanical properties of the parts. Nevertheless, little have been published, once this is a matter of industrial interest. In this work, samples of Fe100-xCux(x=0.40, 0.55, 0.70, 0.85 and 1) alloys were processed by cold pressing at 10 MPa, followed by sintering at 1250 C°. Structures formed during sintering were studied by EDS. Microstructural aspects were observed by MEB. Densification and microhardness tests were also performed.


2021 ◽  
pp. 100184
Author(s):  
Gyanendra Bhatta ◽  
Luis De Los Santos Valladares ◽  
Xinggang Liu ◽  
Zhaojun Ma ◽  
A. Bustamante Domínguez ◽  
...  

Author(s):  
Daimeng Chen ◽  
Kuibao Zhang ◽  
Jianjun Zeng ◽  
Haiyan Guo ◽  
Bo Li ◽  
...  

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