Efficient and green treatment of ultrapure magnetite to prepare powder metallurgy iron powders

2021 ◽  
Vol 378 ◽  
pp. 19-28
Author(s):  
Zhengqi Guo ◽  
Deqing Zhu ◽  
Jian Pan ◽  
Congcong Yang ◽  
Siwei Li ◽  
...  
Metals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 431
Author(s):  
Ahmed Abdallah ◽  
Mahdi Habibnejad-Korayem ◽  
Dmitri V. Malakhov

It is experimentally shown that a removal of particles exceeding 100 microns in size from iron powders typically used in the fabrication of medium density powder metallurgy steels has a weak effect on apparent density, flowability and compressibility of blends as well as on density and strength of green bodies. An elimination of such particles, i.e., cutting off a heavy tail of a size distribution histogram at the 100 μm threshold, improves a compositional uniformity of sintered materials, but has no noticeable beneficial effect upon the strength of a final product, which is likely be determined by a fraction of pores and their shapes. A presence of soft pearlitic inclusions hardly matters unless their number density becomes so large that a 3D continuity (integrity) of a hard martensitic matrix is lost. This finding suggests that such an expensive preparatory step as sieving away large particles from as-received mixtures would bear no technological advantages. It was experimentally found that an attempt to lower the threshold below 100 μm noticeably worsened apparent density, flowability and compressibility.


2021 ◽  
Vol 2131 (4) ◽  
pp. 042024
Author(s):  
M Egorov ◽  
R Egorova ◽  
A Atrohov ◽  
V Ekilik

Abstract At present, powder materials are used in practically all branches of industry, from medicine to aerospace technology. This is a wide range of materials ranging from constructional and instrumental materials and ending with special-purpose materials and medical implants. Powder metallurgy methods are most often used where the manufacture of products with desired properties is impossible using traditional methods: casting, stamping, etc. The production of all these materials is based on such basic operations as: obtaining starting materials, molding from these materials blanks of a given shape, size and strength, and sintering, intended for the final formation of the required properties and dimensions. The peculiarity of powder metallurgy technology allows creating a huge variety of developed technological schemes, which puts these technologies to a new level and allows for the rapid development of many industries. Alloying powder steels, in contrast to cast steels, has a number of characteristic features due to the specificity of their production. The structure of powder alloy steels and their properties depend on the methods of obtaining steels and technological features of their production. The following main methods of obtaining powder alloyed steels can be named: preparation of multicomponent mixtures of powders of iron and alloying elements and their subsequent processing; the use of alloyed iron powders, to which, if necessary, add carbon or other alloying elements; impregnation with liquid alloying metals or diffusion saturation of frameworks sintered from iron powders.


2020 ◽  
Vol 29 (2) ◽  
pp. 1034-1042
Author(s):  
Fang Yang ◽  
Qian Qin ◽  
Haixia Sun ◽  
Peng Liu ◽  
Zhimeng Guo

2014 ◽  
Vol 216 ◽  
pp. 216-221 ◽  
Author(s):  
Bebe Adrian Olei ◽  
Iulian Ştefan ◽  
Nicoleta Popescu

The objective of this research is to observe the influence of the sintering temperature on the wear testing for some steel samples elaborated by powder metallurgy technology. For obtaining the steels there were used iron powders and graphite powders. The powders were homogenized in a high energy ball mill Pulverisette 6, cold compacted and then sintered in a furnace. The sintering parameters are: the sintering temperature, T = (1050, 1100, 1150)°C and the maintaining time, t = 60 minutes. The influence of the sintering parameters on the samples wear behavior is studied using both a tribometer and a profilometer.


Author(s):  
Ivanka Miteva ◽  
Ivan Vinev ◽  
Ivan Mitev

The publication examines the peculiarities of alloying a matrix of water-dispersed iron powders of the type ASC 100.29, AHC 100.29 and ABC 100.30. The possible ways of alloying in powder metallurgy are presented. The influence of the main alloying elements - copper, nickel, phosphorus, molybdenum, etc. was traced. on the technological process in the production of powder metallurgical details. A special place is given to the alloying elements intensifying the process of coagulation of the pores in the matrix during sintering - copper and phosphorus. Graphical dependences for the influence of copper on the dimensional changes of the iron matrix at different sintering temperatures are presented. 


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