scholarly journals Sintering High Green Density Direct Powder Rolled Titanium Strips, in Argon Atmosphere

Metals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 936
Author(s):  
Anthony Govender ◽  
Clinton Bemont ◽  
Silethelwe Chikosha

Presently, the majority of titanium powder metallurgy components produced are sintered under high vacuum due to the associated benefits of the vacuum atmosphere. However, high-vacuum sintering is a batch process, which limits daily production. A higher daily part production is achievable via a continuous sintering process, which uses argon gas to shield the part from air contamination. To date, there has been limited work published on argon gas sintering of titanium in short durations. This study investigated the properties of thin high green density titanium strips, which were sintered at the temperatures of 1100 °C, 1200 °C and 1300 °C for a duration of 30 min, 60 min and 90 min in argon. The strips were produced by rolling of −45 µm near ASTM (American Society for Testing and Materials) grade 3 hydride–dehydride commercially pure titanium powder. The density, hardness, tensile properties and microstructure of the sintered strips were assessed. It was found that near-full densities, between 96 and 99%, are attainable after 30–90 min of sintering. The optimum sintering temperature range was found to be 1100–1200 °C, as this produced the highest elongation of 4–5.5%. Sintering at 1300 °C resulted in lower elongation due to higher contaminant pick-up.

Author(s):  
Kurian Antony ◽  
T Reghunathan Rakeshnath

Laser additive manufacturing processes melt the powder particles using laser beam energy to form solid three-dimensional objects. This article mainly focuses on numerical analysis and experimentation of laser melting of commercially pure titanium powder. Numerical solutions to moving heat source problems were developed, and their influences on process parameters were validated. The energy density has a significant role in laser melting process. The numerical investigation demonstrates the significant effect of laser energy density on laser tracks. The laser power, distribution of powder particles, the absorptivity, density, and chemical constitution of powder materials are the main factors which influence the laser energy penetration. The absorptivity plays a vital role in consolidation phenomena of the powder layer which helps to get a denser part or layer. The experimental result clearly indicates that at lower laser speed the powder compaction is better. Temperature distribution, depth, and width of laser track were compared in this article. By investigating the observations from optical microscopic images and scanning electron microscopic images, the surface characteristics of laser-melted tracks were studied. The study on numerical and experimental results shows that the optimum condition for better laser track is laser power 45 W, laser speed 20 mm/s, and laser diameter 2.5 mm. This study provides important insights into laser parameters in the melting of commercially pure titanium powder.


2021 ◽  
Vol 876 ◽  
pp. 1-6
Author(s):  
Fátima Ternero Fernández ◽  
Petr Urban ◽  
Raquel Astacio Lopez ◽  
Rosa M. Aranda Louvier ◽  
Francisco G. Cuevas

In this work, a commercially pure titanium powder has been consolidated using the Electrical Resistance Sintering (ERS) process. This technique consists in the consolidation of a powder mass by the simultaneous application of pressure (80 MPa, in this work) and heating caused by the passage of a high intensity (3.5-6.0 kA, in this case) and low voltage current (lower than 10 V), during short dwelling times (0.8-1.6 s, in this work). The resulting compacts have been mechanically characterised by measuring their microhardness distribution. The results obtained are compared with the corresponding values of compacts prepared with the same powders following the conventional P/M route of cold pressing and furnace sintering. The results of some simulations are provided to give information about the temperatures reached inside the compacts during the electrical consolidation process.


2014 ◽  
Vol 775-776 ◽  
pp. 13-18 ◽  
Author(s):  
Pâmela Karina dos Santos Bonfim ◽  
Ricardo Ciuccio ◽  
Maurício David Martins das Neves

Titanium is an attractive material for dental and biomedical applications, because of high corrosion resistance, excellent biocompatibility and high mechanical strength combined with low density. However, the high reactivity of titanium in the liquid phase make it difficult to produce it by fusion, so a alternative is powder metallurgy (P/M) method. Powder Metallurgy has been used to manufacture porous implants. The presence of a porous surface is desirable because it improves the osteointegration increases the adhesion between the bone tissue and the implant, being favorable for transporting body fluid. This paper proposes to characterize the commercial pure titanium powder obtained by process of hydride-dehydride, obtain samples with adequate porosity by uniaxial pressing and vacuum sintering and evaluate the corrosion behavior of sintered titanium in Hank ́s solution. The results showed that the titanium powder of angular shape after uniaxial pressing of 400 MPa and sintered in vacuum at 1150 ° C, allowed obtaining samples with adequate surface porosity of around 17%. In potentiodynamic polarization curves revealed no typical behavior of passive metals but show low current density, that increasing corrosion resistance. Keywords: titanium implants, powder metallurgy, porosity and electrochemical behavior.


2019 ◽  
Vol 49 (4) ◽  
pp. 261-268
Author(s):  
Ronei Tochetto ◽  
Rafael Tochetto ◽  
Luciano V. Biehl ◽  
J. L.B. Medeiros ◽  
J. C. Dos Santos ◽  
...  

The objective of this paper is the manufacture of a porous metal structure from commercially pure titanium powder grade 1, aiming at the possible application as a biomaterial in the re-generation of bone tissues assuming its architecture. Exper-imental methods were used to evaluate the effectiveness of the use of the Space Holders tech-nique in the manufacture of powder metallurgy (MP). In the samples produced, 50% by volume of titanium powder and 50% of chemical reagent (So-dium Chloride - NaCl and Ammonium Bicarbonate - HN4HCO3) were added, compressed with a pressure of 250 Mpa. The metal-only test samples were com-pacted with pressures of 70 MPa and 250 MPa. The architecture found with the use of Space Holders was satisfactory, presenting sufficient conditions of size, morphology, and interconnectivity for bone growth within the structure. Samples made only with metal powder do not have enough pores even with lower compation pressure.


2003 ◽  
Vol 51 (6) ◽  
pp. 1651-1662 ◽  
Author(s):  
P. Fischer ◽  
V. Romano ◽  
H.P. Weber ◽  
N.P. Karapatis ◽  
E. Boillat ◽  
...  

2016 ◽  
Vol 704 ◽  
pp. 325-333 ◽  
Author(s):  
Paloma Trueba ◽  
Ernesto Chicardi ◽  
José Antonio Rodríguez-Ortiz ◽  
Juan José Pavón ◽  
Joaquín Cobos ◽  
...  

The manufacture of graded materials has gained an enormous interest during the last decade due to the diversity of industrial and biological materials systems that require or are actually designed to implement that criterion; those natural or artificial materials offer multiple possibilities of applications. In this work, a novel uniaxial and sequential compaction device has been successfully designed and fabricated, in order to obtain samples with three different layers; this new device is suitable for both conventional and non-conventional powder metallurgy (PM) techniques. In addition, this device allowed us to use different combinations of powders and space-holder particles, irrespective of their nature, sizes, morphologies and proportions. It has no restriction about applying different compaction pressures for every layer, which may result in increasing or decreasing porosity. This compaction device is especially powerful if the aim is obtaining samples with radial graded porosity for biomedical applications (replacement of cortical bone involved in different joints and dental restorations) and nuclear applications (mimicking burnt used nuclear fuel). Specifically in this work, different samples with radial graded porosity were fabricated and then microstructurally and mechanically characterized: i) Commercially pure titanium (CP Ti) samples, starting from blends CP Ti with 20 vol.%, 40 vol.% and 60 vol.% of Sodium Chloride (NaCl) as space holder, which were placed in core, intermediate and external layers, respectively; processing conditions were 800 MPa of compaction pressure and 1250 °C for 2h in high vacuum of sintering; and ii) CeO2 samples, starting from blends CeO2 with 0.5 vol.%, 3.0 vol.% and 7.5 vol.% of Ethylene Bis Stearamide (EBS) as space holder, which were placed in core, intermediate and external layers, respectively; processing conditions were 460 MPa in external layer and 700 MPa in core and intermediate layers of compaction pressure, and 1700 °C during 4h in static air of sintering. This new device has proved to have unique advantages for solving problems of structural integrity in conventional PM manufacturing in a simple, economic and reproducible way.


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