Effect of precision casting sand waste of 4140 steel on the sintering and densification behaviour of chamotte refractories

2020 ◽  
Vol 142 (6) ◽  
pp. 2385-2390
Author(s):  
Tuba Bahtli ◽  
Veysel Murat Bostanci
Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1670 ◽  
Author(s):  
Wölfle-Roos JV ◽  
Katmer Amet B ◽  
Fiedler J ◽  
Michels H ◽  
Kappelt G ◽  
...  

Background: Uncemented implants are still associated with several major challenges, especially with regard to their manufacturing and their osseointegration. In this study, a novel manufacturing technique—an optimized form of precision casting—and a novel surface modification to promote osseointegration—calcium and phosphorus ion implantation into the implant surface—were tested in vivo. Methods: Cylindrical Ti6Al4V implants were inserted bilaterally into the tibia of 110 rats. We compared two generations of cast Ti6Al4V implants (CAST 1st GEN, n = 22, and CAST 2nd GEN, n = 22) as well as cast 2nd GEN Ti6Al4V implants with calcium (CAST + CA, n = 22) and phosphorus (CAST + P, n = 22) ion implantation to standard machined Ti6Al4V implants (control, n = 22). After 4 and 12 weeks, maximal pull-out force and bone-to-implant contact rate (BIC) were measured and compared between all five groups. Results: There was no significant difference between all five groups after 4 weeks or 12 weeks with regard to pull-out force (p > 0.05, Kruskal Wallis test). Histomorphometric analysis showed no significant difference of BIC after 4 weeks (p > 0.05, Kruskal–Wallis test), whereas there was a trend towards a higher BIC in the CAST + P group (54.8% ± 15.2%), especially compared to the control group (38.6% ± 12.8%) after 12 weeks (p = 0.053, Kruskal–Wallis test). Conclusion: In this study, we found no indication of inferiority of Ti6Al4V implants cast with the optimized centrifugal precision casting technique of the second generation compared to standard Ti6Al4V implants. As the employed manufacturing process holds considerable economic potential, mainly due to a significantly decreased material demand per implant by casting near net-shape instead of milling away most of the starting ingot, its application in manufacturing uncemented implants seems promising. However, no significant advantages of calcium or phosphorus ion implantation could be observed in this study. Due to the promising results of ion implantation in previous in vitro and in vivo studies, further in vivo studies with different ion implantation conditions should be considered.


Nanomaterials ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1714
Author(s):  
Paweł Wiśniewski

This study presents the general characteristics of binders used in precision casting of Nickel-based superalloys. Three groups of binders were described: resins, organic compounds, and materials containing nanoparticles in alcohol or aqueous systems. This study also includes literature reports on materials commonly used and those recently replaced by water-soluble binders, i.e., ethyl silicate (ES) and hydrolysed ethyl silicate (HES). The appearance of new and interesting solutions containing nano-alumina is described, as well as other solutions at the initial stage of scientific research, such as those containing biopolymers, biodegradable polycaprolactone (PCL), or modified starch. Special attention is paid to four binders containing nano-SiO2 intended for the first layers (Ludox AM, Ludox SK) and structural layers (EHT, Remasol) of shell moulds. Their morphology, viscosity, density, reactions, and electrokinetic potential were investigated. The binders were characterized by a high solid-phase content (>28%), viscosity, and density close to that of water (1–2 mPa·s) and good electrokinetic stability. The nanoparticles contained in the binders were approximately spherically shaped with an average particle size of 16–25 nm.


2012 ◽  
Vol 27 (5) ◽  
pp. 836-840 ◽  
Author(s):  
Debasis Roy ◽  
Biswajoy Bagchi ◽  
Alakananda Bhattacharya ◽  
Sukhen Das ◽  
Papiya Nandy

2009 ◽  
Vol 50 (8) ◽  
pp. 2057-2063 ◽  
Author(s):  
Harumi Tsutsumi ◽  
Mitsuo Niinomi ◽  
Toshikazu Akahori ◽  
Masaaki Nakai ◽  
Tsutomu Takeuchi ◽  
...  
Keyword(s):  

1950 ◽  
Vol 162 (1) ◽  
pp. 66-74 ◽  
Author(s):  
J. S. Turnbull

The paper describes a casting process which differs from standard foundry practice in that it uses a wax pattern in a high refractory one-piece mould to produce metal castings with a good surface finish to an accuracy of ±0·002 inch. The process involves making a master pattern in either hard wood or metal, relating it to a soft metal die by precision casting technique, and then the production of wax patterns from the die on an injection machine. Finally, the wax patterns are invested in refractory moulds, the wax is melted out, the mould baked, and the metal component is cast. The “lost wax” process is advantageous in cases where ( a) the metal is unmachinable, or ( b) where the component is of an unmachinable shape, or ( c) where production by other methods takes too long. One of the most common applications is in the manufacture of gas-turbine blades. The tool costs are relatively low compared to the costs involved in alternative methods of manufacture, the die cost being a function of the number of castings required. The production of cheap castings is necessarily dependent on the scrap percentage being kept to a minimum; at present the scrap from the manufacture of gas-turbine blades is less than 30 per cent, and the author surmises that it would not be unreasonable to expect it to be less than 10 per cent in two years' time.


2021 ◽  
Author(s):  
Liubov Magerramova ◽  
Boris Kozlov ◽  
Eugene Kratt

Abstract Traditionally, the technology used in the production of gas turbine blade castings characterized by a large number of technological conversions, high labor costs with a large amount of manual labor and the need to produce various types of complex and expensive equipment at different stages of production. This work aims to reduce the time and money spent on the manufacturing of ceramic shell shapes — a form suitable for the standard methods of precision casting by traditional heat-resistant nickel alloys. The proposed approached involves obtaining a shell shape with an internal core as a single, non-assembled product, without lengthy and time-consuming design and manufacturing processes involved in forming equipment for the production of castings based on smelted models. The proposed method is based on the use of 3D printing with refractory ceramic pastes. Using both uncooled and cooled blades as examples, models of casting molds were designed, technological processes were developed, and ceramic shell molds were manufactured. Experimental casting into a manufactured ceramic shell mold for an uncooled blade with a bandage shelf was performed and showed satisfactory results.


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