Surface Structure in Microtomed Sections Caused by Glass and Diamond Knives

1971 ◽  
Vol 29 ◽  
pp. 456-457
Author(s):  
J. Temple Black ◽  
William G. Boldosser
Keyword(s):  
Plastic Deformation ◽  
Epoxy Resin ◽  
Carbon Coating ◽  
Surface Damage ◽  
Body Angle ◽  
Normal Manner ◽  
Bottom Side ◽  
Cutting Direction ◽  
Made In ◽  
Diamond Knife

Ultramicrotomy produces plastic deformation in the surfaces of microtomed TEM specimens which can not generally be observed unless special preparations are made. In this study, a typical biological composite of tissue (infundibular thoracic attachment) infiltrated in the normal manner with an embedding epoxy resin (Epon 812 in a 60/40 mixture) was microtomed with glass and diamond knives, both with 45 degree body angle. Sectioning was done in Portor Blum Mt-2 and Mt-1 microtomes. Sections were collected on formvar coated grids so that both the top side and the bottom side of the sections could be examined. Sections were then placed in a vacuum evaporator and self-shadowed with carbon. Some were chromium shadowed at a 30 degree angle. The sections were then examined in a Phillips 300 TEM at 60kv.Carbon coating (C) or carbon coating with chrom shadowing (C-Ch) makes in effect, single stage replicas of the surfaces of the sections and thus allows the damage in the surfaces to be observable in the TEM. Figure 1 (see key to figures) shows the bottom side of a diamond knife section, carbon self-shadowed and chrom shadowed perpendicular to the cutting direction. Very fine knife marks and surface damage can be observed.

Effects of Vibration on the Preparation of Ultrathin Sections

1973 ◽  
Vol 31 ◽  
pp. 358-359
Author(s):  
Joseph M. Blum ◽  
Edward P. Gargiulo ◽  
J. R. Sawers
Keyword(s):  
Cutting Speed ◽  
Ground Level ◽  
Environmental Vibration ◽  
Block Face ◽  
Ultrathin Sections ◽  
Embedding Medium ◽  
Thickness Variations ◽  
Building Walls ◽  
Cutting Direction ◽  
Diamond Knife

It is now well-known that chatter (Figure 1) is caused by vibration between the microtome arm and the diamond knife. It is usually observed as a cyclical variation in “optical” density of an electron micrograph due to sample thickness variations perpendicular to the cutting direction. This vibration might be induced by using too large a block face, too large a clearance angle, excessive cutting speed, non-uniform embedding medium or microtome vibration. Another prominent cause is environmental vibration caused by inadequate building construction. Microtomes should be installed on firm, solid floors. The best floors are thick, ground-level concrete pads poured over a sand bed and isolated from the building walls. Even when these precautions are followed, we recommend an additional isolation pad placed on the top of a sturdy table.

Mechanichal Properties of DGEBA/TEPA Modified Epoxy Resin

2014 ◽  
Vol 775-776 ◽  
pp. 588-592
Author(s):  
Camila Rodrigues Amaral ◽  
Ruben Jesus Sanchez Rodriguez ◽  
Magno Luiz Tavares Bessa ◽  
Verônica Scarpini Cândido ◽  
Sergio Neves Monteiro
Keyword(s):  
Mechanical Properties ◽  
Plastic Deformation ◽  
Epoxy Resin ◽  
Yield Stress ◽  
Diglycidyl Ether ◽  
Notch Toughness ◽  
Epoxy Network ◽  
Structural Network ◽  
Flexural Tests ◽  
Modified Epoxy

The correlation between the structural network of a diglycidyl ether of the bisphenol-A (DGEBA) epoxy resin, modified by two distinct aliphatic amines (tetraethylenepentamine TEPA and jeffamine D230), and its mechanical properties, was investigated as possible matrix for abrasive composites applications. Both flexural tests, to determine the yield stress and the elastic modulus, as well as impact tests to determine the notch toughness, were performed. The DGEBA/D230 presented the highest stiffness and toughness but lowest yield stress. This epoxy network also displayed a greater plastic deformation during fracture.

scholarly journals THE EFFECT OF COCONUT COIR FIBER POWDER CONTENT AND HARDENER WEIGHT FRACTIONS ON MECHANICAL PROPERTIES OF AN EPR-174 EPOXY RESIN COMPOSITE

SINERGI ◽  
2021 ◽  
Vol 25 (3) ◽  
pp. 361
Author(s):  
Muhamad Fitri ◽  
Shahruddin Mahzan ◽  
Imam Hidayat ◽  
Nurato Nurato
Keyword(s):  
Mechanical Properties ◽  
Shear Strength ◽  
Composite Materials ◽  
Impact Strength ◽  
Epoxy Resin ◽  
Resin Composite ◽  
Weight Fraction ◽  
Resin Matrix ◽  
Powder Content ◽  
Made In

The development of composite materials is increasingly widespread, which require superior mechanical properties. From many studies, it is found that the mechanical properties of composite materials are influenced by various factors, including the reinforcement content, both in the form of fibers and particle powder. However, those studies have not investigated the effect of the hardener weight fraction on the mechanical properties of resin composite materials. Even though its function as a hardener is likely to affect its mechanical properties, it might obtain the optimum composition of the reinforcing content and hardener fraction to get the specific mechanical properties. This study examines the effect of hardener weight fraction combined with fiber powder content on mechanical properties of EPR-174 epoxy resin matrix composite and determines the optimum of Them. The research was conducted by testing a sample of composite matrix resin material reinforced with coconut fiber powder. The Powder content was made in 3 levels, i.e.: 6%, 8%, and 10%. While the hardener fraction of resin was made in 3 levels, i.e.: 0.4, 0.5, and 0.6. The test results showed that pure resin had the lowest impact strength of 1.37 kJ/m2. The specimen with a fiber powder content of 6% has the highest impact strength i.e.: 4.92 kJ/m2. The hardener fraction of 0.5 has the highest impact strength i.e.: 4.55 kJ/m2. The fiber powder content of 8% produced the highest shear strength i.e.: 1.00 MPa. Meanwhile, the hardener fraction of 0.6 has the highest shear strength i.e.: 2.03 MPa.

Indentation plastic displacement field: Part I. The case of soft films on hard substrates

1999 ◽  
Vol 14 (6) ◽  
pp. 2196-2203 ◽  
Author(s):  
T. Y. Tsui ◽  
Joost Vlassak ◽  
William D. Nix
Keyword(s):  
Plastic Deformation ◽  
Cross Sections ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Porous Titanium ◽  
Titanium Layer ◽  
Plastic Deformation Behavior ◽  
Plastic Displacement ◽  
Film Substrate ◽  
Made In

The plastic deformation behavior of Knoop indentations made in a soft, porous titanium/aluminum multilayered thin film on a hard silicon substrate is studied through use of the focused-ion-beam milling and imaging technique. Pileup is observed for indentations with depths larger than 30% of the total film thickness. Analysis of the indentation cross sections shows that plastic deformation around the indentation is partly accommodated by the closing of the pores within the multilayers. This densification process reduces the amount of pileup formed below that predicted by finite element simulations. Experimental results show that the pileup is formed by an increase of the titanium layer thickness near the edges of the indentation. The thickness increase is largest near the film/substrate interface and decreases toward the surface of the multilayered film. The amount of normal compression near the center of the indenter is characterized, and it is demonstrated that the deformation becomes more nonuniform with increasing indentation depth.

Hole Surface Quality and Damage When Drilling Unidirectional CFRP Composites

2012 ◽  
Author(s):  
Eshetu D. Eneyew ◽  
M. Ramulu
Keyword(s):  
Significant Variation ◽  
Thrust Force ◽  
Cutting Speed ◽  
Polycrystalline Diamond ◽  
Surface Damage ◽  
Fiber Reinforced Plastic ◽  
Reinforced Plastic ◽  
Cfrp Composite ◽  
Cutting Direction

In this study, an experimental investigation on the drilling of unidirectional carbon fiber reinforced plastic (UD-CFRP) composite was conducted using polycrystalline diamond (PCD) tipped eight facet drill. The quality of the drilled hole surface was examined through surface roughness measurements and surface damage by scanning electron microscopy (SEM). It was found that, fiber pullout occurred in two specific sectors relative to the angle between the cutting direction and the fiber orientation. The thrust force was highly influenced by the feed rate than the cutting speed and it shows a significant variation throughout the rotation of the drill.

Stresses in a Medium Speed Diesel Engine Frame

1976 ◽  
Vol 190 (1) ◽  
pp. 309-318
Author(s):  
H. Fessler ◽  
M. Perla
Keyword(s):  
Diesel Engine ◽  
Epoxy Resin ◽  
Load Paths ◽  
Qualitative Understanding ◽  
Medium Speed ◽  
Compression Springs ◽  
Inertia Forces ◽  
Made In

SYNOPSIS The bedplate, column, cylinder casings, bearing caps and crankshaft of a model of one bay of a Vee type medium speed Diesel engine have been made in epoxy resin and joined by compression springs simulating the appropriate bolt forces and stiffnesses. The model has been loaded by freely hanging weights simulating firing and reciprocating inertia forces and subjected to frozen stress loading. Stresses obtained from numerous slices cut from these components are analysed and related to the designer's qualitative understanding of the load paths.

scholarly journals Fundamental mechanisms of surface damage associated to the localization of the plastic deformation in fatigue

2010 ◽  
Vol 2 (1) ◽  
pp. 751-757 ◽  
Author(s):  
H.S. Ho ◽  
M. Risbet ◽  
X. Feaugas ◽  
J. Favergeon ◽  
G. Moulin
Keyword(s):  
Plastic Deformation ◽  
Surface Damage

Cut Surface Damage to Metals from Diamond Knife Ultramicrotomy

1967 ◽  
Vol 25 ◽  
pp. 360-361
Author(s):  
J. A. Hugo ◽  
V. A. Phillips
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Recent Work ◽  
Light Microscope ◽  
Cumulative Effect ◽  
Surface Damage ◽  
Damage Layer ◽  
Transmission Electron ◽  
Cut Surface ◽  
Diamond Knife

Recent work in our laboratory has shown that cut surfaces which are perfect when viewed in the light microscope may be prepared by ultramicrotomy using a diamond knife. Alloys successfully examined include Pb-Sn, Sn-Bi, Al-Mg, Cu-Al, and Cu-Co. After a normal etch, a Sn-5% Bi alloy showed no damage by replication electron microscopy over extensive areas. Although the cut surface may be flat, the question of whether or not there is an internally damaged layer remains unanswered. This is particularly pertinent to the use of ultramicrotomed slices for transmission electron microscopy, since damage left on the cut surface would be incorporated in the next slice cut, furthermore, if the damage layer were deep there could be a cumulative effect, so that damage from two or more previous cuts could be incorporated in a slice, in addition to that resulting from the shear during cutting.

Tribological Properties of KDP Single Crystal

2014 ◽  
Vol 490-491 ◽  
pp. 134-137
Author(s):  
Chun Peng Lu ◽  
Hang Gao ◽  
Xiao Ji Teng
Keyword(s):  
Plastic Deformation ◽  
Single Crystal ◽  
Tribological Properties ◽  
Room Temperature ◽  
Surface Damage ◽  
Kdp Crystal ◽  
Scratch Tests ◽  
Elastic And Plastic Deformation ◽  
Kdp Crystals

Scratch tests on (001) face, doubler face and tripler face of KDP crystals are carried out at room temperature. It shows that the friction ceoffcients of different crystal faces are affected seriously by the crystal oritations, their variation periods of (001) face, doubler face and tripler face are 90o, 180o and 180o, their attitudes of relative anisotropy are 50%, 43.8% and 43.8%, and all of them are less than 0.4. The scratch mechanism of KDP crystal consists of four types: elastic and plastic deformation, ploughing, microchip, and surface damage. Differences between elastic and plastic deformation and ploughing are not obvious due to the soft-brittle nature of KDP crystal.

scholarly journals Numerical Investigations of Stress Concentration in Reinforcement Steel Structure by Composite Overlays

2019 ◽  
Vol 26 (4) ◽  
pp. 249-256
Author(s):  
Bogdan Szybiński ◽  
Mateusz Wygoda
Keyword(s):  
Stress Concentration ◽  
Epoxy Resin ◽  
Steel Structure ◽  
Resin Matrix ◽  
Fibre Reinforcement ◽  
Element Analysis ◽  
Premature Failure ◽  
Epoxy Resin Matrix ◽  
Stress Concentration Factors ◽  
Made In

AbstractThe stress concentration observed in the vicinity of cut-outs and holes in structural elements significantly influences the fatigue endurance of machines subjected to cyclic loads. Numerous studies have been made so far to improve this situation and increase the structure lifetime. Several design recommendations have also been worked out to avoid the problem of premature failure. The proposed article illustrates the influence of the composite overlays applied around the cut-outs made in flat steel constructional elements subjected to axial tension. The detailed study concerns the reinforcement made from the FRP (fibre reinforcement polymer) composite applied around the notches. Two types of composite materials were used, namely: TVR 380 M12/R-glass (glass fibres embedded in epoxy resin matrix) and AS4D/9310 (carbon fibres embedded in epoxy resin matrix). In the first step, the detailed numerical studies (finite element analysis) were performed for the steel samples (with no overlays added) with cut-outs made in the form of circle, square and triangle hole (the last two with rounded corners). The results of these studies were compared with the existing analytical solutions with respect to the stress concentration factors (SCF) estimation. The relatively good conformity was observed when using dense meshes of finite elements placed around the void vicinity. In the next step, the composite overlays were applied around cut-outs and their influence on the stress concentration was investigated. The influence of the fibre orientation, numbers of layers, sizes of the composite overlay used were considered. It was proved that the application of composite overlays evidently decreases the stress concentration around the notches.

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