The Experts below are selected from a list of 22584 Experts worldwide ranked by ideXlab platform
Maurilio Marcacci - One of the best experts on this subject based on the ideXlab platform.
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Pulsed Plasma Deposition of Zirconia Thin Films on the Plastic Component of Low Wear Joint Prostheses
Journal of Bone and Joint Surgery-british Volume, 2013Co-Authors: Alessandro Russo, Michele Bianchi, Nicola Lopomo, Maria Cristina Maltarello, Alessandro Ortolani, Maurilio MarcacciAbstract:Introduction When osteoarthritis occurs, joint replacement is the most frequent treatment. Currently, the mean survival rate for total joint arthroplasty is ∼90% after 10 years: the main reason for long-term implant failure, that generally required a revision surgery, are osteolysis and aseptic loosening of the implant, which are strongly correlated with wear debris formation from the UHMWPE insert [Ingham, 2005], as a consequence of the cyclic loading against the metallic or ceramic counterface [Dumbleton, 2002]. Wear debris bring to chronic inflammation of periprosthetic tissues causing an increase of bone reabsorption that finally provoke aseptic loosening, so implant failure[Holt, 2007]. Different solutions were proposed to reduce wear debris production but agreement has not been achieved yet. Our challenging approach prefigures the direct coating of the Plastic Component with a hard and well-adherent ceramic film, in order to drastically reduce wear debris formation from the Plastic substrate while preserving its well-established bulk mechanical properties, especially under high local loads [Bianchi, 2013]. Methods 3%yttria-stabilized zirconia films were deposited by PPD technique. PPD is a new vapour deposition technique based on the ablation of a target material as a consequence of the impact of a high-energy electron beam. The plasma plume of ablated material is directed toward and deposited onto the substrate. Films were characterized by SEM-EDX, X-ray diffraction, nanoindentation, adhesion and tribological tests. Moreover, capability of ZrO2–UHMWPE system of carrying local loads – i.e. an estimation of the resistance to a third-body abrasion – was investigated. Results X-ray diffraction measurements revealed that zirconia films grew in cubic phase, while scanning electron microscopy images showed a dense, columnar film microstructure, exhibiting a nanostructured top surface (grain size Moreover, preliminary tribological tests carried out in air against an alumina ball counterpart showed wear rate as low as 3.2*10 −6 mm3N −1 m −1 after 500.000 cycles. Conclusions We have presented the preliminary results of a novel approach aiming to the drastic reduction of Plastic debris release from common joint prostheses. The results showed suggested the feasibility of pursuing this alternative and completely new route to improve UHMPWE performances while preserving its well-established mechanical properties. Hard and well-adherent zirconia films deposited directly on the surface of Plastic Component of a joint implant will allow a drastic reduction of wear debris production and Plastic deformation of the Component, without weakening primary and secondary stability of the implant.
Alessandro Russo - One of the best experts on this subject based on the ideXlab platform.
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Pulsed Plasma Deposition of Zirconia Thin Films on the Plastic Component of Low Wear Joint Prostheses
Journal of Bone and Joint Surgery-british Volume, 2013Co-Authors: Alessandro Russo, Michele Bianchi, Nicola Lopomo, Maria Cristina Maltarello, Alessandro Ortolani, Maurilio MarcacciAbstract:Introduction When osteoarthritis occurs, joint replacement is the most frequent treatment. Currently, the mean survival rate for total joint arthroplasty is ∼90% after 10 years: the main reason for long-term implant failure, that generally required a revision surgery, are osteolysis and aseptic loosening of the implant, which are strongly correlated with wear debris formation from the UHMWPE insert [Ingham, 2005], as a consequence of the cyclic loading against the metallic or ceramic counterface [Dumbleton, 2002]. Wear debris bring to chronic inflammation of periprosthetic tissues causing an increase of bone reabsorption that finally provoke aseptic loosening, so implant failure[Holt, 2007]. Different solutions were proposed to reduce wear debris production but agreement has not been achieved yet. Our challenging approach prefigures the direct coating of the Plastic Component with a hard and well-adherent ceramic film, in order to drastically reduce wear debris formation from the Plastic substrate while preserving its well-established bulk mechanical properties, especially under high local loads [Bianchi, 2013]. Methods 3%yttria-stabilized zirconia films were deposited by PPD technique. PPD is a new vapour deposition technique based on the ablation of a target material as a consequence of the impact of a high-energy electron beam. The plasma plume of ablated material is directed toward and deposited onto the substrate. Films were characterized by SEM-EDX, X-ray diffraction, nanoindentation, adhesion and tribological tests. Moreover, capability of ZrO2–UHMWPE system of carrying local loads – i.e. an estimation of the resistance to a third-body abrasion – was investigated. Results X-ray diffraction measurements revealed that zirconia films grew in cubic phase, while scanning electron microscopy images showed a dense, columnar film microstructure, exhibiting a nanostructured top surface (grain size Moreover, preliminary tribological tests carried out in air against an alumina ball counterpart showed wear rate as low as 3.2*10 −6 mm3N −1 m −1 after 500.000 cycles. Conclusions We have presented the preliminary results of a novel approach aiming to the drastic reduction of Plastic debris release from common joint prostheses. The results showed suggested the feasibility of pursuing this alternative and completely new route to improve UHMPWE performances while preserving its well-established mechanical properties. Hard and well-adherent zirconia films deposited directly on the surface of Plastic Component of a joint implant will allow a drastic reduction of wear debris production and Plastic deformation of the Component, without weakening primary and secondary stability of the implant.
E. Smith - One of the best experts on this subject based on the ideXlab platform.
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The use of eta factors to describe the J integral for the bend specimen
Engineering Fracture Mechanics, 1993Co-Authors: E. SmithAbstract:Abstract A theoretical analysis for the bend specimen geometry shows that a single eta factor description for the Plastic Component J DP of the deformation integral J D for a non-growing crack is an accurate description if b / W ≲ 0.5, with b = ligament width and W = specimen width. This conclusion, which is supportive of the appropriate ASTM standard, is consistent with a similar conclusion for the compact tension specimen geometry. With such a J DP description, both J DP and J M crack growth resistance curves can be obtained from load, load-point displacement and crack extension measurements using a single specimen.
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An Appraisal of a Recent Analysis for Estimating the Plastic Component of the Deformation J Integral for a Stationary Crack
Journal of Engineering Materials and Technology, 1991Co-Authors: E. SmithAbstract:This paper provides an appraisal of a recent analysis for estimating the Plastic Component of the deformation J integral for a stationary crack. Such an estimation is a prerequisite when describing ductile crack extension in nuclear reactor pressure vessel materials. The assumptions in the analysis are emphasized, and the approximations arising as a consequence of introducing these assumptions are demonstrated.
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The Plastic Component of the deformation J-integral for a stationary crack: The small-scale yielding situation
International Journal of Engineering Science, 1991Co-Authors: E. SmithAbstract:Abstract Against the background of the desirability of having a reliable methodology for quantifying a material's crack growth resistance, the paper derives a general expression which relates the Plastic Component J P of the deformation J integral ( J D ) for a stationary crack to the crack tip stress intensity, when the yielding is small-scale; J P can then be expressed in terms of the energy integral via a composite eta factor η COMP . It is thereby possible to examine the overall accuracy of eta factor descriptions of J P , that are obtained on the basis of limit load considerations; the paper examines the accuracy for the compact tension specimen geometry. More generally, the small-scale yielding results can be coupled with those for the extensive yield state, so as to give a simple procedure for obtaining the two eta factors η and η c appropriate to a two eta factor description of J P .
Alessandro Ortolani - One of the best experts on this subject based on the ideXlab platform.
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Pulsed Plasma Deposition of Zirconia Thin Films on the Plastic Component of Low Wear Joint Prostheses
Journal of Bone and Joint Surgery-british Volume, 2013Co-Authors: Alessandro Russo, Michele Bianchi, Nicola Lopomo, Maria Cristina Maltarello, Alessandro Ortolani, Maurilio MarcacciAbstract:Introduction When osteoarthritis occurs, joint replacement is the most frequent treatment. Currently, the mean survival rate for total joint arthroplasty is ∼90% after 10 years: the main reason for long-term implant failure, that generally required a revision surgery, are osteolysis and aseptic loosening of the implant, which are strongly correlated with wear debris formation from the UHMWPE insert [Ingham, 2005], as a consequence of the cyclic loading against the metallic or ceramic counterface [Dumbleton, 2002]. Wear debris bring to chronic inflammation of periprosthetic tissues causing an increase of bone reabsorption that finally provoke aseptic loosening, so implant failure[Holt, 2007]. Different solutions were proposed to reduce wear debris production but agreement has not been achieved yet. Our challenging approach prefigures the direct coating of the Plastic Component with a hard and well-adherent ceramic film, in order to drastically reduce wear debris formation from the Plastic substrate while preserving its well-established bulk mechanical properties, especially under high local loads [Bianchi, 2013]. Methods 3%yttria-stabilized zirconia films were deposited by PPD technique. PPD is a new vapour deposition technique based on the ablation of a target material as a consequence of the impact of a high-energy electron beam. The plasma plume of ablated material is directed toward and deposited onto the substrate. Films were characterized by SEM-EDX, X-ray diffraction, nanoindentation, adhesion and tribological tests. Moreover, capability of ZrO2–UHMWPE system of carrying local loads – i.e. an estimation of the resistance to a third-body abrasion – was investigated. Results X-ray diffraction measurements revealed that zirconia films grew in cubic phase, while scanning electron microscopy images showed a dense, columnar film microstructure, exhibiting a nanostructured top surface (grain size Moreover, preliminary tribological tests carried out in air against an alumina ball counterpart showed wear rate as low as 3.2*10 −6 mm3N −1 m −1 after 500.000 cycles. Conclusions We have presented the preliminary results of a novel approach aiming to the drastic reduction of Plastic debris release from common joint prostheses. The results showed suggested the feasibility of pursuing this alternative and completely new route to improve UHMPWE performances while preserving its well-established mechanical properties. Hard and well-adherent zirconia films deposited directly on the surface of Plastic Component of a joint implant will allow a drastic reduction of wear debris production and Plastic deformation of the Component, without weakening primary and secondary stability of the implant.
Michele Bianchi - One of the best experts on this subject based on the ideXlab platform.
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Pulsed Plasma Deposition of Zirconia Thin Films on the Plastic Component of Low Wear Joint Prostheses
Journal of Bone and Joint Surgery-british Volume, 2013Co-Authors: Alessandro Russo, Michele Bianchi, Nicola Lopomo, Maria Cristina Maltarello, Alessandro Ortolani, Maurilio MarcacciAbstract:Introduction When osteoarthritis occurs, joint replacement is the most frequent treatment. Currently, the mean survival rate for total joint arthroplasty is ∼90% after 10 years: the main reason for long-term implant failure, that generally required a revision surgery, are osteolysis and aseptic loosening of the implant, which are strongly correlated with wear debris formation from the UHMWPE insert [Ingham, 2005], as a consequence of the cyclic loading against the metallic or ceramic counterface [Dumbleton, 2002]. Wear debris bring to chronic inflammation of periprosthetic tissues causing an increase of bone reabsorption that finally provoke aseptic loosening, so implant failure[Holt, 2007]. Different solutions were proposed to reduce wear debris production but agreement has not been achieved yet. Our challenging approach prefigures the direct coating of the Plastic Component with a hard and well-adherent ceramic film, in order to drastically reduce wear debris formation from the Plastic substrate while preserving its well-established bulk mechanical properties, especially under high local loads [Bianchi, 2013]. Methods 3%yttria-stabilized zirconia films were deposited by PPD technique. PPD is a new vapour deposition technique based on the ablation of a target material as a consequence of the impact of a high-energy electron beam. The plasma plume of ablated material is directed toward and deposited onto the substrate. Films were characterized by SEM-EDX, X-ray diffraction, nanoindentation, adhesion and tribological tests. Moreover, capability of ZrO2–UHMWPE system of carrying local loads – i.e. an estimation of the resistance to a third-body abrasion – was investigated. Results X-ray diffraction measurements revealed that zirconia films grew in cubic phase, while scanning electron microscopy images showed a dense, columnar film microstructure, exhibiting a nanostructured top surface (grain size Moreover, preliminary tribological tests carried out in air against an alumina ball counterpart showed wear rate as low as 3.2*10 −6 mm3N −1 m −1 after 500.000 cycles. Conclusions We have presented the preliminary results of a novel approach aiming to the drastic reduction of Plastic debris release from common joint prostheses. The results showed suggested the feasibility of pursuing this alternative and completely new route to improve UHMPWE performances while preserving its well-established mechanical properties. Hard and well-adherent zirconia films deposited directly on the surface of Plastic Component of a joint implant will allow a drastic reduction of wear debris production and Plastic deformation of the Component, without weakening primary and secondary stability of the implant.