Preparation of Molybdenum High Speed Tool Steels with Addition of Niobium Carbide by Powder Metallurgy Techniques

2014 ◽  
Vol 802 ◽  
pp. 102-107 ◽  
Author(s):  
Oscar Olimpio de Araújo Filho ◽  
Rodrigo Tecchio Antonello ◽  
Cezar Henrique Gonzalez ◽  
Severino Leopoldino Urtiga Filho ◽  
Francisco Ambrozio Filho
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Powder Metallurgy ◽  
Liquid Phase ◽  
High Speed ◽  
Niobium Carbide ◽  
High Energy ◽  
Tool Steels ◽  
Vacuum Sintering ◽  
Scanning Electron

High speed steels processed by Powder Metallurgy (PM) techniques present better mechanical properties when compared with similar steels obtained by the conventional process of cast to ingot and hot working. PM techniques produce improved microstructures with smaller and better distribution of carbides. Liquid phase sintering high speed steel seems to be a cheaper processing route in the manufacturing of tool steels if compared to the well-known and expansive hot isostatic pressing high speed steels. The introduction of niobium as alloying element began with the object of replacing elements like vanadium (V) and tungsten (W). Phase liquid sintering consists in a manufacturing technique to process high speed steels by powder metallurgy. The aim of this work of research is to process and obtain AISI M2 and M3:2 with and without the addition of niobium carbide by high energy milling, cold uniaxial compaction and vacuum sintering in the presence of a liquid phase. The powders of the AISI M2 and M3:2 were processed by high energy milling adding a small quantity of niobium carbide (6% in mass), then the powders were characterized by means of X-ray diffraction (XRD) and scanning electron Microscopy (SEM) plus energy dispersion spectroscopy (EDS) in order to evaluate the milling process. The powders of the AISI M2 and M3:2 with the addition of niobium carbide (NbC) were uniaxially cold compacted and then submitted to vacuum sintering. The sintered samples had their microstructure, porosity and carbide distribution observed and evaluated by means of Scanning Electron Microscopy (SEM) and the mechanical property of hardness was investigated by means of Vickers hardness tests. At least five samples of each steel were investigated.

Influence of Cutting Edge Radius on the Wear Resistance of Powder Metallurgy High-Speed Steel Milling Inserts

2006 ◽  
Vol 220 (3) ◽  
pp. 383-387 ◽  
Author(s):  
J Rech ◽  
M-J Schaff
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Powder Metallurgy ◽  
High Speed ◽  
High Speed Steel ◽  
Cutting Edge ◽  
Wear Behaviour ◽  
Cutting Inserts ◽  
Cutting Speeds ◽  
Scanning Electron

The wear behaviour of powder metallurgy high-speed steel (PM-HSS) milling inserts is investigated experimentally. Cutting inserts with different cutting edge radii tested at various feed rates and cutting speeds were examined. The radii have been obtained either by microsandblasting or by honing. The initiation and progress of the tool wear was analysed with scanning electron microscopy (SEM) of the cutting edges. The experimental results exhibit quantitatively the effect of tool radius on the performance of milling inserts. A radius on the cutting edge prevents fast and unpredictable wear, and can lead to a great improvement of the tool life.

Processing of Metal Matrix AA2124 Aluminium Alloy Composites Reinforced by Alumina and Silicon Carbide by Powder Metallurgy Techniques

2014 ◽  
Vol 802 ◽  
pp. 84-89 ◽  
Author(s):  
Sérvulo José Ferreira Alves ◽  
Marcio Marcelo Sampaio de Sousa ◽  
Everthon Rodrigues de Araújo ◽  
Francisco Ambrozio Filho ◽  
Maurílio José dos Santos ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Silicon Carbide ◽  
Powder Metallurgy ◽  
Aluminium Alloy ◽  
Metal Matrix ◽  
High Energy ◽  
Vacuum Furnace ◽  
Scanning Electron

This work aims the processing of metal matrix AA2124 aluminium alloy composites reinforced by alumina (Al2O3) and silicon carbide (SiC). The composites were manufactured by powder metallurgy techniques, in a grinding using a ball mill spex type (high energy) at a ratio of balls/ powders of 10:1 and grinding time of 30 and 60 minutes using stearic acid (C18H36O2) as lubricant to each one of the samples. The fractions used in both reinforcements were 5, 10 and 15% in mass. The microstructural characterizations of AA2124 alloy powders with the reinforcements of alumina (Al2O3) and silicon carbide (SiC) powders were obtained by scanning electron microscopy (SEM) and the particles sizes and distribuition of the particle sizes in powders produced were obtained by laser diffraction, whereas the sintered characterizations were obtained by scanning electron microscopy (SEM) and mechanical characterization of the sintered tests was achieved by Vickers hardness (HV). The composites were uniaxially cold compacted (room temperature), at a pressure of 7.0 t / cm2, thus forming small pellets that were sintered (at a temperature of 500 °C) in a vacuum furnace at IPEN (SP). There was observed the influence of the respective bulk fractions of reinforcement particles used in mechanical characteristics presented in the resulting composites.

The bright future of digital imaging in scanning electron microscopy

1993 ◽  
Vol 51 ◽  
pp. 768-769
Author(s):  
M. T. Postek ◽  
A. E. Vladar
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Digital Imaging ◽  
High Speed ◽  
High Performance ◽  
Mass Storage ◽  
Analog To Digital ◽  
Central Processing ◽  
Digital Imaging Technology ◽  
Scanning Electron

One of the major advancements applied to scanning electron microscopy (SEM) during the past 10 years has been the development and application of digital imaging technology. Advancements in technology, notably the availability of less expensive, high-density memory chips and the development of high speed analog-to-digital converters, mass storage and high performance central processing units have fostered this revolution. Today, most modern SEM instruments have digital electronics as a standard feature. These instruments, generally have 8 bit or 256 gray levels with, at least, 512 × 512 pixel density operating at TV rate. In addition, current slow-scan commercial frame-grabber cards, directly applicable to the SEM, can have upwards of 12-14 bit lateral resolution permitting image acquisition at 4096 × 4096 resolution or greater. The two major categories of SEM systems to which digital technology have been applied are:In the analog SEM system the scan generator is normally operated in an analog manner and the image is displayed in an analog or "slow scan" mode.

Spin-polarized Scanning Electron Microscopy

1990 ◽  
Vol 48 (4) ◽  
pp. 768-769
Author(s):  
Kazuyuki Koike ◽  
Hideo Matsuyama
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
High Speed ◽  
Magnetic Thin Films ◽  
Electron Spin Polarization ◽  
Acquisition Time ◽  
Magnetization Direction ◽  
Spin Polarized ◽  
Conventional Methods ◽  
Scanning Electron

Spin-polarized scanning electron microscopy (spin SEM), where the secondary electron spin polarization is used as the image signal, is a novel technique for magnetic domain observation. Since its first development by Koike and Hayakawa in 1984, several laboratories have extensively studied this technique and have greatly improved its capability for data extraction and its range of applications. This paper reviews the progress over the last few years.Almost all the high expectations initially held for spin SEM have been realized. A spatial resolution of several hundreds angstroms has been attained, which is nearly one order of magnitude higher than that of conventional methods for thick samples. Quantitative analysis of magnetization direction has been performed more easily than with conventional methods. Domain observation of the surface of three-dimensional samples has been confirmed to be possible. One of the drawbacks, a long image acquisition time, has been eased by combining highspeed image-signal processing with high speed scanning, although at the cost of image quality. By using spin SEM, the magnetic structure of a 180 degrees surface Neel wall, magnetic thin films, multilayered films, magnetic discs, etc., have been investigated.

scholarly journals Characterization by Scanning Electron Microscopy on Drill Boride and Drilling Performance of Tool Steels

2020 ◽  
Vol 26 (S2) ◽  
pp. 388-390
Author(s):  
Victor Olmos Domínguez ◽  
Marco Doñu Ruiz ◽  
Noe Lopez Perrusquia ◽  
Leopoldo Garcia Vanegas
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Tool Steels ◽  
Drilling Performance ◽  
Scanning Electron

Titanium Effect on Microstructure and Fracture toughness of Al2O3-BASED Composites

2011 ◽  
Vol 691 ◽  
pp. 32-36
Author(s):  
José G. Miranda-Hernández ◽  
Elizabeth Refugio-García ◽  
Eduardo Térres-Rojas ◽  
Enrique Rocha-Rangel
Keyword(s):  
Electron Microscopy ◽  
Fracture Toughness ◽  
Scanning Electron Microscopy ◽  
Fine Particles ◽  
Ceramic Matrix ◽  
High Energy ◽  
Titanium Content ◽  
Indentation Method ◽  
Sintered Temperature ◽  
Scanning Electron

The effect of different titanium additions (0.5, 1, 2, 3 and 10 vol. %), milling intensity (4 and 8 h) and sintered temperature (1500 and 1600 °C) on microstructure and fracture toughness of Al2O3-based composites was analyzed in this study. After high energy milling of a titanium and Al2O3mixtures, powder mixture presents fine distribution and good homogenization between ceramic and metal. After milling powders during 8 h they were obtained very fine particles with 200 nm average sizes. Microstructures of the sintered bodies were analyzed with a scanning electron microscopy, where it was observed that the microstructure presents the formation of a small and fine metallic net inside the ceramic matrix. From fracture toughness measurements realized by the fracture indentation method, it had that when titanium content in the composite increases, fracture toughness is enhanced until 83% with respect to the fracture toughness of pure Al2O3. This behavior is due to the formation of metallic bridges by titanium in the Al2O3matrix.

The Fracture Failure Analysis of Precision Centrifuge Spindle

2014 ◽  
Vol 971-973 ◽  
pp. 802-805
Author(s):  
Wei Feng Zhang ◽  
Li Yan ◽  
Fu Xia Zhang
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Chemical Composition ◽  
Fracture Mechanics ◽  
Failure Analysis ◽  
Fatigue Failure ◽  
High Speed ◽  
Experimental Results ◽  
Fracture Failure ◽  
Scanning Electron

For the problem of high-speed rotating centrifuge spindle fracture failures, relevant analyses are conducted from the perspective of microstructure, chemical composition and fracture mechanics by using scanning electron microscopy and related instruments. Experimental results and analyses indicate that the spindle fracture is fatigue failure, mainly caused by cold cracks generated on the journal surfacing. Based on the analysis results, improvements and measures are suggested to better solve the spindle weld fracture failure problems.

Mechanochemical Synthesis of Intermetallic Compounds in the Gallium–Iridium System

2019 ◽  
Vol 18 (03n04) ◽  
pp. 1940067
Author(s):  
P. Vitiaz ◽  
N. Lyakhov ◽  
T. Grigoreva ◽  
E. Pavlov
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Mechanical Activation ◽  
Intermetallic Compounds ◽  
High Energy ◽  
Planetary Mill ◽  
X Ray Diffraction ◽  
X Ray ◽  
Active Liquid ◽  
Scanning Electron

The interaction between a solid inert metal Ir and an active liquid metal Ga during mechanical activation in a high-energy planetary mill is studied by X-ray diffraction and scanning electron microscopy with high-resolution energy dispersive X-ray microanalysis. The effect of mechanical activation on the formation of GaxIry intermetallic compounds and GaxIry/Ir composites and their solubility in acids was investigated. The subsequent extraction of Ga from intermetallic compounds and composites in the mixture of concentrated acids [Formula: see text] makes it possible to produce nanoscale Ir.

Synthesis of Cu/Cr and Cu/Cr/W Materials by Powder Metallurgy Techniques

2018 ◽  
Vol 880 ◽  
pp. 241-247
Author(s):  
Claudiu Nicolicescu ◽  
Victor Horia Nicoară ◽  
Costel Silviu Bălulescu
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Scanning Electron Microscopy ◽  
Powder Metallurgy ◽  
Chemical Composition ◽  
Electrical Properties ◽  
Mechanical Alloying ◽  
Ball Mill ◽  
Weight Percent ◽  
Scanning Electron

Alloys based on Cu/Cr and Cu/Cr/W attract the attention due to their presence in different applications that require higher electrical properties which are combined with good mechanical properties. In order to synthesis the material based on Cu/Cr and Cu/Cr/W, mechanical alloying technique was used. Four mixtures, X1 (99%CuCr), X2 (97%CuCr), X3 (94%Cu1%CrW), X4 (92%Cu3%CrW – weight percent), were prepared using a vario planetary ball mill Pulverisette 4 made by Fritsch. The mixtures obtained after 10 hours were analyzed by scanning electron microscopy (SEM). It was found that the presence of chromium and tungsten influence the morphology and the particles tend to be flat. Sinter ability and microhardness are influenced by the chemical composition of the samples.

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