Correlation between the Energy Input and the Microstructure of Additively Manufactured Cobalt-Chromium

2017 ◽  
Vol 379 ◽  
pp. 157-165 ◽  
Author(s):  
Leonhard Hitzler ◽  
Philipp Williams ◽  
Markus Merkel ◽  
Wayne Hall ◽  
Andreas Öchsner
Keyword(s):  
Fibre Laser ◽  
Cobalt Chromium ◽  
Recent Trial ◽  
Cocrmo Alloy ◽  
Powder Bed ◽  
Fine Grained ◽  
Medical Sector ◽  
Manufacturing Techniques ◽  
Fabrication Parameters ◽  
Made In

Powder-bed based additive manufacturing techniques are of high interest for the medical sector and recent trial studies have shown their feasibility. Due to the rapid improvements made in the machinery and the related changes in the type and characteristics of the utilized power source, optimizations regarding the fabrication parameters tend to differ amongst various machines. In this study, a parameter optimization was undertaken for a biocompatible dental CoCrMo alloy on a SLM 280HL machine, featuring a 400 W fibre laser. It was shown that the availability of higher laser powers enables a more energy efficient fabrication. Moreover, parameter sets for fast and economic fabrication, as well as for high density and fine-grained microstructure, were defined.

scholarly journals Effect of Digital Technologies on the Marginal Accuracy of Conventional and Cantilever Co–Cr Posterior-Fixed Partial Dentures Frameworks

2021 ◽  
Vol 11 (7) ◽  
pp. 2988
Author(s):  
Celia Tobar ◽  
Verónica Rodríguez ◽  
Carlos Lopez-Suarez ◽  
Jesús Peláez ◽  
Jorge Cortés-Bretón Brinckmann ◽  
...  
Keyword(s):  
Digital Technologies ◽  
Hard Metal ◽  
Direct Metal Laser Sintering ◽  
Cobalt Chromium ◽  
Metal Ceramic ◽  
Marginal Discrepancy ◽  
Soft Metal ◽  
Manufacturing Techniques ◽  
Ceramic Restorations ◽  
To Receive

The introduction of new digital technologies represents an important advance to fabricate metal–ceramic restorations. However, few studies have evaluated the influence of these technologies on the fit of the restorations. The aim of this study was to evaluate the effect of different manufacturing techniques and pontic design on the vertical marginal fit of cobalt–-chromium (Co–Cr) posterior fixed partial dentures (FPDs) frameworks. Methods: Eighty stainless-steel dies were prepared to receive 3-unit FPDs frameworks with intermediate pontic (n = 40) and cantilever pontic (n = 40). Within each design, the specimens were randomly divided into four groups (n = 10 each) depending on the manufacturing technique: casting (CM), direct metal laser sintering (LS), soft metal milling (SM), and hard metal milling (HM). The frameworks were luted, and the vertical marginal discrepancy was assessed. Data analysis was made using Kruskal–Wallis and Mann–Whitney U tests (α = 0.05). Results: The vertical marginal discrepancy values of all FPDs were below 50 μm. The HM frameworks obtained the lowest misfit values in both designs. However, no differences were found among intermediate pontic groups or cantilevered groups. Likewise, when differences in a marginal discrepancy between both framework designs were analyzed, no differences were observed. Conclusions: The analyzed digital technologies demonstrated high precision of fit on Co–Cr frameworks and on both pontic designs.

scholarly journals Corrosion Behavior of LENS Deposited CoCrMo Alloy Using Bayesian Regularization-Based Artificial Neural Network (BRANN)

2021 ◽  
Vol 7 (3) ◽  
Author(s):  
Nagoor Basha Shaik ◽  
Kedar Mallik Mantrala ◽  
Balaji Bakthavatchalam ◽  
Qandeel Fatima Gillani ◽  
M. Faisal Rehman ◽  
...  
Keyword(s):  
Neural Network ◽  
Artificial Neural Network ◽  
Corrosion Rate ◽  
Prediction Models ◽  
Test Time ◽  
Bayesian Regularization ◽  
Cobalt Chromium ◽  
Corrosion Properties ◽  
Cocrmo Alloy ◽  
Artificial Neural

AbstractThe well-known fact of metallurgy is that the lifetime of a metal structure depends on the material's corrosion rate. Therefore, applying an appropriate prediction of corrosion process for the manufactured metals or alloys trigger an extended life of the product. At present, the current prediction models for additive manufactured alloys are either complicated or built on a restricted basis towards corrosion depletion. This paper presents a novel approach to estimate the corrosion rate and corrosion potential prediction by considering significant major parameters such as solution time, aging time, aging temperature, and corrosion test time. The Laser Engineered Net Shaping (LENS), which is an additive manufacturing process used in the manufacturing of health care equipment, was investigated in the present research. All the accumulated information used to manufacture the LENS-based Cobalt-Chromium-Molybdenum (CoCrMo) alloy was considered from previous literature. They enabled to create a robust Bayesian Regularization (BR)-based Artificial Neural Network (ANN) in order to predict with accuracy the material best corrosion properties. The achieved data were validated by investigating its experimental behavior. It was found a very good agreement between the predicted values generated with the BRANN model and experimental values. The robustness of the proposed approach allows to implement the manufactured materials successfully in the biomedical implants.

Using Molding to Fabricate Stable Salt Structures for Thermochemical Energy Storage

2021 ◽  
Author(s):  
Adam Gladen ◽  
Fardad Azarmi
Keyword(s):  
Energy Storage ◽  
Sintering Temperature ◽  
Hydration Reaction ◽  
Half Cycle ◽  
Cycle Stability ◽  
Manufacturing Techniques ◽  
Hygroscopic Salts ◽  
Fabrication Parameters ◽  
Molded Sample ◽  
Stable Structures

Abstract The present work investigates using a molding technique to fabricate stable salt structures for thermochemical energy storage. Two type of salts were investigated: pure MgSO4 and a blend of 53% CaCl2 with 47% MgSO4. These salts were mixed with two common binders and hot pressed. Various post-hot-pressing conditions were considered including the debinding temperature, whether the sample was sintered, and the sintering temperature. The samples were subjected to combined hydration and thermal cycling. The hydration reaction was monitored by measuring the relative humidity. The samples were visibly inspected for changes between each half cycle. The results indicate that molding can result in stable structures. All the samples of 53wt%CaCl2+47%wtMgSO4 and one sample of pure MgSO4 retained their integrity through the course of cycling. Of the samples that did not retain their integrity through cycling, the results show that fabrication parameters can be used to improve the cycle stability of the molded sample. The hydration data shows that, for the samples that retained their structure, stable hydration rates were achieved. This indicates that the structure stabilized. These results show the feasibility of using molding or similar manufacturing techniques to fabricate a stable structure of hygroscopic salts for thermochemical-based, thermal energy storage.

scholarly journals Peri-implant cartilage and bone histological changes following treatment of focal osteochondral defects in the femoral head with polyether ether ketone implants versus cobalt chromium molybdenum alloy implants: assessment in a goat model

2020 ◽  
Author(s):  
Zhiguo Yuan ◽  
Wei Zhang ◽  
Xiangchao Meng ◽  
Jue Zhang ◽  
Teng TengLong ◽  
...  
Keyword(s):  
Femoral Head ◽  
Osteochondral Defect ◽  
Osteochondral Defects ◽  
Cobalt Chromium ◽  
Cocrmo Alloy ◽  
Polyether Ether Ketone ◽  
Histological Score ◽  
Ether Ketone ◽  
Cobalt Chromium Molybdenum

Abstract Objective: This study aimed to quantitatively investigate the peri-implant histology of applying defect-size polyether ether ketone (PEEK) implant for the treatment of localized osteochondral defects in the femoral head and compared it with cobalt chromium molybdenum (CoCrMo) alloy implant.Methods: A femoral head osteochondral defect model was created in the left hips of goats (n=12). Defects were randomly treated by immediate placement of a PEEK (n=6) or CoCrMo implant (n=6). The un-operated right hip joints served as a control. Goats were sacrificed at 12 weeks. Periprosthetic cartilage quality was semi-quantitatively analyzed macroscopically and microscopically. Implant osseointegration was measured by micro-CT and histomorphometry.Results: The modified macroscopic articular evaluation score in the PEEK group was lower than that in the CoCrMo group (p<0.05), and the histological score of the periprosthetic and acetabular cartilage in the PEEK group was lower than that in the CoCrMo group (P<0.05). The mean bone-implant contact for PEEK implants was comparable with that for CoCrMo alloy implants at 12 weeks.Conclusions: A PEEK implant for the treatment of local osteochondral defect in the femoral head demonstrated effective fixation and superior in vivo cartilage protection compared with an identical CoCrMo alloy implant.

scholarly journals Corrosion and Corrosion Fatigue Properties of Additively Manufactured Magnesium Alloy WE43 in Comparison to Titanium Alloy Ti-6Al-4V in Physiological Environment

Materials ◽  
2019 ◽  
Vol 12 (18) ◽  
pp. 2892 ◽  
Author(s):  
Nils Wegner ◽  
Daniel Kotzem ◽  
Yvonne Wessarges ◽  
Nicole Emminghaus ◽  
Christian Hoff ◽  
...  
Keyword(s):  
Titanium Alloy ◽  
Fatigue Strength ◽  
Magnesium Alloy ◽  
Corrosion Fatigue ◽  
Fatigue Properties ◽  
Test Duration ◽  
Medical Sector ◽  
Manufacturing Techniques ◽  
Alloy We43 ◽  
Application Fields

Laser powder bed fusion (L-PBF) of metals enables the manufacturing of highly complex geometries which opens new application fields in the medical sector, especially with regard to personalized implants. In comparison to conventional manufacturing techniques, L-PBF causes different microstructures, and thus, new challenges arise. The main objective of this work is to investigate the influence of different manufacturing parameters of the L-PBF process on the microstructure, process-induced porosity, as well as corrosion fatigue properties of the magnesium alloy WE43 and as a reference on the titanium alloy Ti-6Al-4V. In particular, the investigated magnesium alloy WE43 showed a strong process parameter dependence in terms of porosity (size and distribution), microstructure, corrosion rates, and corrosion fatigue properties. Cyclic tests with increased test duration caused an especially high decrease in fatigue strength for magnesium alloy WE43. It can be demonstrated that, due to high process-induced surface roughness, which supports locally intensified corrosion, multiple crack initiation sites are present, which is one of the main reasons for the drastic decrease in fatigue strength.

Channel design for 3D models with applications in powder-bed additive manufacturing

2019 ◽  
Vol 25 (9) ◽  
pp. 1536-1544
Author(s):  
Xiangzhi Wei ◽  
Xianda Li ◽  
Shanshan Wen ◽  
Yu Zheng ◽  
Yaobin Tian
Keyword(s):  
Additive Manufacturing ◽  
3D Model ◽  
3D Models ◽  
Linear Constraints ◽  
Channel Design ◽  
Channel Network ◽  
Content Type ◽  
Powder Bed ◽  
Shortest Network ◽  
Manufacturing Techniques

Purpose For any 3D model with chambers to be fabricated in powder-bed additive manufacturing processes such as SLM and SLS, powders are trapped in the chambers of the finished model. This paper aims to design a shortest network with the least number of outlets for efficiently leaking the trapped powders. Design/methodology/approach This paper proposes a nonlinear objective with linear constraints for solving the channel design problem and a particle swarm optimization algorithm to solve the nonlinear system. Findings Structural optimization for the channel network leads to fairly short channels in the interior of the 3D models and very few outlets on the model surface, which achieves the cleaning of the powders while causing almost the least changes to the model. Originality/value This paper reveals the NP-harness of computing the shortest channel network with the least number of outlets. The proposed approach helps the design of lightweight models using the powder-bed additive manufacturing techniques.

scholarly journals Finite element analysis in defining the optimal shape and safety factor of retentive clasp arms of removable partial denture

2013 ◽  
Vol 70 (11) ◽  
pp. 999-1005
Author(s):  
Miodrag Scepanovic ◽  
Ljiljana Tihacek-Sojic ◽  
Milan Tasic ◽  
Radivoje Mitrovic ◽  
Aleksandar Todorovic ◽  
...  
Keyword(s):  
Stress Distribution ◽  
Safety Factor ◽  
Computer Aided Design ◽  
Pure Titanium ◽  
Commercially Pure Titanium ◽  
Cobalt Chromium ◽  
Removable Partial Denture ◽  
Cocrmo Alloy ◽  
Partial Denture ◽  
Cocrmo Alloys

Bacground/Aim. Retentive force of removable partial denture (RPD) directly depends on elastic force of stretched retentive clasp arms (RCAs). During deflection RCA must have even stress distribution. Safety factor is the concept which can be applied in estimating durability and functionality of RCAs. This study was based on analyzing properties of clasps designed by conventional clasp wax profiles and defining the optimal shapes of RCAs for stress distribution and safety factor aspects. Methods. Computer-aided-design (CAD) models of RCAs with simulated properties of materials used for fabrication of RPD cobalt-chromium-molybdenum (CoCrMo) alloy, commercially pure titanium (CPTi) and polyacetale were analyzed. Results. The research showed that geometrics of Rapidflex profiles from the BIOS concept are defined for designing and modeling RCAs from CoCrMo alloys. I-Bar and Bonihard clasps made from CPTi might have the same design as Co- CrMo clasp only by safety factor aspect, but it is obvious that CPTi are much more flexible, so their shape must be more massive. Polyacetale clasps should not be fabricated by BIOS concept for CoCrMo alloy. A proof for that is the low value of safety factor. Conclusion. The BIOS concept should be used only for RCAs made of CoCrMo alloy and different wax profiles should be used for fabricating clasps of other investigated materials. The contribution of this study may be the improvement of present systems for defining the clasps shapes made from CoCrMo alloys. The more significant application is possibility of creating new concepts in defining shapes of RCA made from CPTi and polyacetale.

Effect of nAl2O3 on the part density and microstructure during the laser-based powder bed fusion of AlSi10Mg composite

2020 ◽  
Vol 26 (4) ◽  
pp. 727-735 ◽  
Author(s):  
Zhenglin Du ◽  
Hui-Chi Chen ◽  
Ming Jen Tan ◽  
Guijun Bi ◽  
Chee Kai Chua
Keyword(s):  
Energy Density ◽  
Complex Geometry ◽  
Electron Backscatter Diffraction ◽  
Grain Structure ◽  
Powder Bed Fusion ◽  
Research Attention ◽  
Fusion Technique ◽  
Content Type ◽  
Powder Bed ◽  
Manufacturing Techniques

Purpose In recent years, additive manufacturing techniques have attracted much research attention because of their ability to fabricate customised parts with complex geometry. The range of composites suitable for laser-based powder bed fusion technique is limited, and has not been investigated yet. This paper aims to study the fabrication of AlSi10Mg reinforced with nAl2O3 using the laser-based powder bed fusion technique. Design/methodology/approach An experimental approach was used to investigate the densification of AlSi10Mg–nAl2O3 composites using laser-based powder bed fusion technique. Optimisation of the porosity was performed, and microstructure evolution was evaluated. Findings In this study, laser volumetric energy density (approximately 109 J/mm3) was found to be required for the fabrication of AlSi10Mg–nAl2O3 composites with a relative volumetric density approximating 99%. The use of laser volumetric energy density resulted in larger grains. Columnar grain structure was observed via the use of electron backscatter diffraction mapping. Originality/value This paper examines the processing of new aluminium composite material suitable for the fabrication via the laser-based powder bed fusion technique.

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