Effects of Burnishing Pattern on Surface Integrity in Microforming of Biodegradable Bone Implants

2011 ◽  
Author(s):  
M. Salahshoor ◽  
Y. B. Guo
Keyword(s):  
Surface Roughness ◽  
Surface Integrity ◽  
Structural Integrity ◽  
Bulk Material ◽  
Biological Response ◽  
The Body ◽  
Important Process ◽  
Micro Forming ◽  
Implant Surface ◽  
Biodegradable Magnesium

When a medical device is implanted into the human body, either hard or soft tissue, the body will respond to the device surface. While the bulk material of the device is often important for structural integrity, the device surface is at the interface with biology function. Major effort has been spent modifying an implant surface in order to control a biological response. Metallic biodegradable Magnesium-Calcium (MgCa) alloys have attracted an increased attention for orthopedic fixation applications. This research focuses on plastic burnishing as a novel micro forming technique that is tune surface integrity to control biodegradation as a biological response. The effects of burnishing pattern as an important process parameter on surface integrity characteristics such as surface roughness, surface topography, microstracture, microhardness, and residual stresses are investigated.

Surface Integrity of Biodegradable Magnesium-Calcium (Mg-Ca) Alloy by Low Plasticity Burnishing

2010 ◽  
Author(s):  
M. Salahshoor ◽  
Y. B. Guo
Keyword(s):  
Surface Roughness ◽  
Residual Stresses ◽  
Surface Integrity ◽  
Bulk Material ◽  
Large Diameter ◽  
Biological Response ◽  
The Body ◽  
Low Plasticity Burnishing ◽  
Sever Plastic Deformation ◽  
Biodegradable Magnesium

When a device is implanted into the body, into either hard or soft tissue, the body will respond. While the bulk material of the device is often important for integrity and mechanical success, the device surface is at the interface with biology. Major effort has been spent modifying a biomaterial surface in order to elicit or inhibit a biological response. Metallic biodegradable Magnesium-Calcium (Mg-Ca) alloys have attracted an increased attention for orthopedic fixation applications. This research focuses on low plasticity burnishing (LPB) as a novel surface modification technique that is added to the surface to control biodegradation as a biological response. The effects of burnishing pressure as an important process parameter on surface integrity characteristics such as surface roughness, surface topography, and residual stresses are investigated. Burnished surface roughness is smaller than the machined ones. However, some amount of waviness is observed which might be due to large diameter of the burnishing ball and sever plastic deformation. High compressive residual stresses are measured on the burnished surface.

A Study of Surface Integrity when Machining Refractory Titanium Alloys

2009 ◽  
Vol 83-86 ◽  
pp. 1059-1068 ◽  
Author(s):  
Armansyah Ginting ◽  
Mohammed Nouari ◽  
Nadhir Lebaal
Keyword(s):  
Surface Roughness ◽  
Titanium Alloys ◽  
Surface Integrity ◽  
Bulk Material ◽  
Cutting Speed ◽  
Cutting Condition ◽  
Feed Speed ◽  
Machined Surface ◽  
Feed Mark ◽  
Coated Carbide

In this paper, the surface integrity is studied when machining the aeronautical titanium alloys. Surface roughness, lay, defects, microhardness and microstructure alterations are studied. The result of surface roughness judges that the CVD-coated carbide fails to produce better Ra value than the uncoated. Lay is characterized by cutting speed and feed speed directions. Feed mark, tearing surface, chip layer formation as built up layer (BUL), and deposited microchip are the defects. Microhardness is altered down to 350 microns beneath the machined surface. The first 50 microns is the soft sub-surface caused by thermal softening in ageing process. Microstructure alteration is observed in this sub-surface. Down to 200 microns is the hard sub-surface caused by the cyclic internal work hardening and then it is gradually decreasing to the bulk material hardness. It is concluded that dry machining titanium alloy is possible using uncoated carbide with cutting condition limited to finish or semi-finish for minimizing surface integrity alteration.

Surface Integrity of End Milled Ti-6Al-4V Using the TiAlN Coated Tool

2008 ◽  
Author(s):  
Y. B. Guo ◽  
Jie Sun
Keyword(s):  
Surface Roughness ◽  
Surface Integrity ◽  
End Milling ◽  
Bulk Material ◽  
Cutting Speed ◽  
Depth Of Cut ◽  
Near Surface ◽  
Β Phase ◽  
Radial Depth ◽  
Milled Surface

End milling titanium Ti-6Al-4V has wide applications in aerospace, biomedical, and chemical industries. However, milling induced surface integrity has received little attention. In this study, a series of end milling experiment were conducted to comprehensively characterize surface integrity at various milling conditions. The experimental results have shown that the milled surface shows the anisotropic nature with a surface roughness range in 0.6 μm–1.2 μm. Surface roughness increases with feed and radial depth-of-cut (DoC), but varies with the cutting speed range. Compressive residual normal stress occurs in both cutting and feed directions, while the influences of cutting speed and feed on residual stress trend are quit different. The microstructure analysis shows that β phase becomes much smaller and severely deformed in the very near surface with the cutting speed. The milled surfaces are at least 60% harder than the bulk material in the subsurface.

scholarly journals Er,Cr:YSGG Laser Performance Improves Biological Response on Titanium Surfaces

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 756
Author(s):  
Wan-Ling Yao ◽  
Jerry Chin Yi Lin ◽  
Eisner Salamanca ◽  
Yu-Hwa Pan ◽  
Pei-Yo Tsai ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Laser Treatment ◽  
Photoelectron Spectroscopy ◽  
Osteoblast Differentiation ◽  
Biological Response ◽  
Water Soluble ◽  
Implant Surface ◽  
Bacterial Structure ◽  
Titanium Surfaces ◽  
Electronic Microscope

Porphyromonas gingivalis infection is one of the causes of implant failures, which can lead to peri-implantitis. Implant surface roughness is reportedly related strongly to P. gingivalis adhesion, which can lead to peri-implantitis and, later, cell adhesion. Our aim was to evaluate the effects of Er,Cr:YSGG laser on titanium (Ti) disc surfaces and its interaction with bacterial adhesion and fibroblast viability. Ti discs underwent two treatments: autoclaving (control) and erbium, chromium-doped yttrium scandium gallium garnet (Er,Cr:YSGG) laser treatment (test). Ti disc surfaces were examined with scanning electronic microscope (SEM), Energy-dispersive spectrometry (EDX), X-ray photoelectron spectroscopy (XPS). The surface roughness same as wettability were also investigated. Fibroblast viability was assessed with the water-soluble tetrazolium 1 (WST-1) test, and osteoblast differentiation was assessed with the alkaline phosphatase (ALP) assay. Bacterial structure and colony formation were detected with scanning electron microscopy and Gram stain. In comparison to control discs, the test discs showed smoother surfaces, with 0.25-µm decrease in surface roughness (p < 0.05); lower P. gingivalis adhesion (p < 0.01); less P. gingivalis colonization (p < 0.05); and increased fibroblast viability and osteoblast differentiation (p < 0.05). Er,Cr:YSGG laser treatment improved disc surfaces by making them slightly smoother, which reduced P. gingivalis adhesion and increased fibroblast viability and osteoblast differentiation. Er,Cr:YSGG laser treatment can be considered a good option for managing peri-implantitis. Further investigations of laser-assisted therapy are necessary for better guidelines in the treatment of peri-implantitis.

Images and Applications of Ion Explosion Spike Pits

1990 ◽  
Vol 48 (1) ◽  
pp. 584-585
Author(s):  
P. Fraundorf ◽  
J. Tentschert
Keyword(s):  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
Bulk Material ◽  
Coulomb Repulsion ◽  
The Body ◽  
Atomic Scale ◽  
Early Solar System ◽  
Transmission Electron ◽  
Nuclear Particle ◽  
Particle Tracks

Since the discovery of their etchability in the early 1960‘s, nuclear particle tracks in insulators have had a diverse and exciting history of application to problems ranging from the selective filtration of cancer cells from blood to the detection of 244Pu in the early solar system. Their usefulness stems from the fact that they are comprised of a very thin (e.g. 20-40Å) damage core which etches more rapidly than does the bulk material. In fact, because in many insulators tracks are subject to radiolysis damage (beam annealing) in the transmission electron microscope, the body of knowledge concerning etched tracks far outweighs that associated with latent (unetched) tracks in the transmission electron microscope.With the development of scanned probe microscopies with lateral resolutions on the near atomic scale, a closer look at the structure of unetched nuclear particle tracks, particularly at their point of interface with solid surfaces, is now warranted and we think possible. The ion explosion spike model of track formation, described loosely, suggests that a burst of ionization along the path of a charged particle in an insulator creates an electrostatically unstable array of adjacent ions which eject one another by Coulomb repulsion from substitutional into interstitial sites. Regardless of the mechanism, the ejection process which acts to displace atoms along the track core seems likely to operate at track entry and exit surfaces, with the added feature of mass loss at those surfaces as well. In other words, we predict pits whose size is comparable to the track core width.

Impact of medical titanium implant surface on the efficiency of fibrointegration

2020 ◽  
pp. 50-55
Author(s):  
T. R. Davydova ◽  
А. I. Shaikhaliev ◽  
D. A. Usatov ◽  
G. A. Gasanov ◽  
R. S. Korgoloev
Keyword(s):  
Surface Roughness ◽  
Titanium Dioxide ◽  
Rough Surface ◽  
Soft Tissues ◽  
Titanium Implant ◽  
Implant Surface ◽  
Anatase Structure ◽  
Bioactive Coating ◽  
Cell Structures ◽  
Titanium Alloy Ti6al4v

The aim of this study was to study the effect of surface branching of titanium endoprostheses on the efficiency of fibrointegration. The object of the study was samples of titanium alloy Ti6Al4V in the form of disks with a diameter of 5 mm and a thickness of 1 mm with various surface treatments: 1) samples with a rough surface after sandblasting; 2) samples with a rough surface after sandblasting with a bioactive coating of titanium dioxide TiO2 with anatase structure. The study of surface roughness was carried out by profilometry. Evaluation of the spreading and proliferation of cells on the surface of test samples, as well as evaluation of the effectiveness of fibrointegration was carried out according to standard methods using scanning electron microscopy. During the experiments, mesinchymal stem cells were sown on test samples and the test samples were introduced into the soft tissues of experimental animals. Based on the results obtained, it was concluded that the technology of forming rough surfaces by sandblasting does not provide high uniformity and reproducibility in the nanometer range and, apparently, another method for obtaining a rough surface should be chosen. The application of a bioactive coating of titanium dioxide TiO2 with the anatase structure to the surface of titanium endoprostheses increases the efficiency of fibrointegration, however, primarily the fibrointegration of titanium endoprostheses depends on their surface roughness, which determines the concentration of cell structures, the intensity of their adhesion and the ability to fibrointegrative process.

scholarly journals Influence of turning tool wear on the surface integrity and anti-fatigue behavior of Ti1023

2021 ◽  
Vol 13 (4) ◽  
pp. 168781402110112
Author(s):  
Li Xun ◽  
Wang Ziming ◽  
Yang Shenliang ◽  
Guo Zhiyuan ◽  
Zhou Yongxin ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Plastic Deformation ◽  
Titanium Alloy ◽  
Fatigue Life ◽  
Tool Wear ◽  
Surface Integrity ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Machined Surface ◽  
Deformation Layer

Titanium alloy Ti1023 is a typical difficult-to-cut material. Tool wear is easy to occur in machining Ti1023, which has a significant negative effect on surface integrity. Turning is one of the common methods to machine Ti1023 parts and machined surface integrity has a direct influence on the fatigue life of parts. To control surface integrity and improve anti-fatigue behavior of Ti1023 parts, it has an important significance to study the influence of tool wear on the surface integrity and fatigue life of Ti1023 in turning. Therefore, the effect of tool wear on the surface roughness, microhardness, residual stress, and plastic deformation layer of Ti1023 workpieces by turning and low-cycle fatigue tests were studied. Meanwhile, the influence mechanism of surface integrity on anti-fatigue behavior also was analyzed. The experimental results show that the change of surface roughness caused by worn tools has the most influence on anti-fatigue behavior when the tool wear VB is from 0.05 to 0.25 mm. On the other hand, the plastic deformation layer on the machined surface could properly improve the anti-fatigue behavior of specimens that were proved in the experiments. However, the higher surface roughness and significant surface defects on surface machined utilizing the worn tool with VB = 0.30 mm, which leads the anti-fatigue behavior of specimens to decrease sharply. Therefore, to ensure the anti-fatigue behavior of parts, the value of turning tool wear VB must be rigorously controlled under 0.30 mm during finishing machining of titanium alloy Ti1023.

scholarly journals The Influence of Bloom Index, Endotoxin Levels and Polyethylene Glycol Succinimidyl Glutarate Crosslinking on the Physicochemical and Biological Properties of Gelatin Biomaterials

Biomolecules ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1003
Author(s):  
Zhuning Wu ◽  
Stefanie H. Korntner ◽  
Jos Olijve ◽  
Anne Maria Mullen ◽  
Dimitios I. Zeugolis
Keyword(s):  
Elastic Modulus ◽  
Polyethylene Glycol ◽  
Enzymatic Degradation ◽  
Structural Integrity ◽  
Biological Response ◽  
Biological Properties ◽  
Compression Stress ◽  
Free Amine ◽  
Amine Content ◽  
Physicochemical And Biological Properties

In the medical device sector, bloom index and residual endotoxins should be controlled, as they are crucial regulators of the device’s physicochemical and biological properties. It is also imperative to identify a suitable crosslinking method to increase mechanical integrity, without jeopardising cellular functions of gelatin-based devices. Herein, gelatin preparations with variable bloom index and endotoxin levels were used to fabricate non-crosslinked and polyethylene glycol succinimidyl glutarate crosslinked gelatin scaffolds, the physicochemical and biological properties of which were subsequently assessed. Gelatin preparations with low bloom index resulted in hydrogels with significantly (p < 0.05) lower compression stress, elastic modulus and resistance to enzymatic degradation, and significantly higher (p < 0.05) free amine content than gelatin preparations with high bloom index. Gelatin preparations with high endotoxin levels resulted in films that induced significantly (p < 0.05) higher macrophage clusters than gelatin preparations with low endotoxin level. Our data suggest that the bloom index modulates the physicochemical properties, and the endotoxin content regulates the biological response of gelatin biomaterials. Although polyethylene glycol succinimidyl glutarate crosslinking significantly (p < 0.05) increased compression stress, elastic modulus and resistance to enzymatic degradation, and significantly (p < 0.05) decreased free amine content, at the concentration used, it did not provide sufficient structural integrity to support cell culture. Therefore, the quest for the optimal gelatin crosslinker continues.

scholarly journals A methodology for hygrothermal modelling of imperfect masonry interfaces

2021 ◽  
pp. 174425912198938
Author(s):  
Michael Gutland ◽  
Scott Bucking ◽  
Mario Santana Quintero
Keyword(s):  
Boundary Conditions ◽  
Material Properties ◽  
Structural Integrity ◽  
Bulk Material ◽  
Weather Conditions ◽  
Masonry Wall ◽  
Two Dimensional ◽  
Liquid Transport ◽  
Imperfect Contact ◽  
Moisture Contents

Hygrothermal models are important tools for assessing the risk of moisture-related decay mechanisms which can compromise structural integrity, loss of architectural features and material. There are several sources of uncertainty when modelling masonry, related to material properties, boundary conditions, quality of construction and two-dimensional interactions between mortar and unit. This paper examines the uncertainty at the mortar-unit interface with imperfections such as hairline cracks or imperfect contact conditions. These imperfections will alter the rate of liquid transport into and out of the wall and impede the liquid transport between mortar and masonry unit. This means that the effective liquid transport of the wall system will be different then if only properties of the bulk material were modelled. A detailed methodology for modelling this interface as a fracture is presented including definition of material properties for the fracture. The modelling methodology considers the combined effect of both the interface resistance across the mortar-unit interface and increase liquid transport in parallel to the interface, and is generalisable to various combinations of materials, geometries and fracture apertures. Two-dimensional DELPHIN models of a clay brick/cement-mortar masonry wall were created to simulate this interaction. The models were exposed to different boundary conditions to simulate wetting, drying and natural cyclic weather conditions. The results of these simulations were compared to a baseline model where the fracture model was not included. The presence of fractures increased the rate of absorption in the wetting phase and an increased rate of desorption in the drying phase. Under cyclic conditions, the result was higher peak moisture contents after rain events compared to baseline and lower moisture contents after long periods of drying. This demonstrated that detailed modelling of imperfections at the mortar-unit interface can have a definitive influence on results and conclusions from hygrothermal simulations.

scholarly journals Skewness and Kurtosis: Important Parameters in the Characterization of Dental Implant Surface Roughness—A Computer Simulation

2011 ◽  
Vol 2011 ◽  
pp. 1-6 ◽  
Author(s):  
Karl Niklas Hansson ◽  
Stig Hansson
Keyword(s):  
Surface Roughness ◽  
Shear Strength ◽  
Roughness Parameter ◽  
Interface Shear Strength ◽  
Interface Shear ◽  
Implant Surface ◽  
Bone Response ◽  
Dental Implant Surface ◽  
Skewness And Kurtosis

The surface roughness affects the bone response to dental implants. A primary aim of the roughness is to increase the bone-implant interface shear strength. Surface roughness is generally characterized by means of surface roughness parameters. It was demonstrated that the normally used parameters cannot discriminate between surfaces expected to give a high interface shear strength from surfaces expected to give a low interface shear strength. It was further demonstrated that the skewness parameter can do this discrimination. A problem with this parameter is that it is sensitive to isolated peaks and valleys. Another roughness parameter which on theoretical grounds can be supposed to give valuable information on the quality of a rough surface is kurtosis. This parameter is also sensitive to isolated peaks and valleys. An implant surface was assumed to have a fairly well-defined and homogenous “semiperiodic” surface roughness upon which isolated peaks were superimposed. In a computerized simulation, it was demonstrated that by using small sampling lengths during measurement, it should be possible to get accurate values of the skewness and kurtosis parameters.

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