The Effect of Fatigue Loading on the Interfacial Shear Properties of SCS-6/Ti-Based MMCS

1992 ◽  
Vol 273 ◽  
Author(s):  
Pete Kantzos ◽  
J. Eldridge ◽  
D. A. Koss ◽  
L. J. Ghosn
Keyword(s):  
Shear Strength ◽  
Interfacial Shear Strength ◽  
Fiber Strength ◽  
Fatigue Loading ◽  
Growth Conditions ◽  
Interfacial Shear ◽  
Interfacial Damage ◽  
Carbon Coatings ◽  
Interfacial Sliding ◽  
Wear Damage

ABSTRACTFractographic analysis of SCS-6/Ti-24Al-11 Nb(a/o) (Ti-24-11 hereafter) and SCS-6/Ti-1 5V- 3Cr-3Al-3Sn(w/o) (Ti-15-3 hereafter) composites subjected to fatigue crack growth conditions indicates that the interface is prone to wear damage as a result of fiber/matrix sliding. In this study, the effect of fatigue loading on the integrity of the Interface was studied by using fiber pushout testing to compare the interfacial shear strength of composite specimens in the asreceived condition with specimens that were previously subjected to fatigue loading. Fatigue loading was also simulated by pushing fibers back and forth (multiple reverse pushouts). It was concluded that interfacial sliding during fatigue loading results in interfacial damage and degradation of the interfacial shear strength. Tensile testing of extracted fibers exposed to fatigue-induced interfacial damage was also performed to determine the effect of interface damage on the fiber strength. Interfacial damage also resulted in decreased fiber strength of the SCS-6 fiber. Fracture and wear of the outer carbon coatings on the SCS-6 fiber is the main contributing factor in the deterioration of these interfaces.

Effect of Coating Thickness on Interfacial Shear Behavior of Zirconia-Coated Sapphire Fibers in a Polycrystalline Alumina Matrix

1994 ◽  
Vol 365 ◽  
Author(s):  
John R. Hellmann ◽  
Yeong-Shyung Chou
Keyword(s):  
Heat Treatment ◽  
Shear Strength ◽  
Coating Thickness ◽  
Interfacial Shear Strength ◽  
Interfacial Shear ◽  
Alumina Matrix ◽  
Stick Slip ◽  
Polycrystalline Alumina ◽  
Fiber Coating ◽  
Interfacial Sliding

ABSTRACTThe effect of zirconia (ZrO2) interfacial coatings on the interfacial shear behavior in sapphire reinforced alumina was examined in this study. Zirconia coatings of thicknesses ranging from 0.15 to 1.45 μm were applied to single crystal sapphire (Saphikon) fibers using a particulate loaded sol dipping technique. After calcining at 1100°C in air, the coated fibers were incorporated into a polycrystalline alumina matrix via hot pressing. Interfacial shear strength and sliding behavior of the coated fibers was examined using thin-slice indentation fiber pushout and pushback techniques. In all cases, debonding and sliding occurred at the interface between the fibers and the coating. The coatings exhibited a dense microstructure and led to a higher interfacial shear strength (> 240 MPa) and interfacial sliding stress (>75 MPa) relative to previous studies on the effect of a porous interphase on interfacial properties [1]. The interfacial shear strength decreased with increasing fiber coating thickness (from 389 ± 59 to 241 ± 43 MPa for 0.15 to 1.45 μm thick coatings, respectively). Sliding behavior exhibited load modulation with increasing displacement during fiber sliding which is characteristic of fiber roughnessinduced “stick-slip”. No effect of fiber coating thickness on the interfacial sliding stress was observed for single pushout or pushback events. Heat treatment at 1550°C in air coarsened the fiber surface roughness, resulting in significantly higher interfacial shear strengths (>30%) and interfacial sliding stresses (>60%) relative to the coated fibers in an as-hot-pressed condition. Interfacial sliding resistance decreased significantly after the first sliding cycle. Evidence of substantial “stick-slip” behavior was eliminated from the load displacement plots after one pushout/pushback cycle; however, the pushback plots exhibited evidence of fiber reseating, followed by a decreasing trend in load with increasing displacement of the fiber back to the original position. These results directly support the interphase fragmentation scenario proposed for interface fatigue in ceramic composites.The high interfacial shear strengths and sliding stresses measured in this study, as well as the potentially strength degrading surface reconstruction observed on the coated fibers after hot pressing and heat treatment, indicate that dense zirconia coatings are not suitable candidates for optimizing composite toughness and strength in the sapphire fiber reinforced alumina system.

Fiber-matrix interface reinforcement using Atomic Layer Deposition

2013 ◽  
Vol 1499 ◽  
Author(s):  
Sari Katz ◽  
Yacov Carmiel ◽  
Irina Gouzman ◽  
Chaim N. Sukenik ◽  
Hanoch D. Wagner ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Shear Strength ◽  
Atomic Layer Deposition ◽  
Aluminum Oxide ◽  
Interfacial Shear Strength ◽  
Fiber Strength ◽  
Atomic Layer ◽  
Interfacial Shear ◽  
Layer Deposition ◽  
Fiber Matrix

ABSTRACTThe interface between a matrix and its reinforcement is critical to the final composite properties. There are different ways to enhance bonding between the reinforcing fiber and the matrix, based mainly on surface plasma treatments which usually decrease the fiber tensile strength. In this research, atomic layer deposition (ALD) was tested as a possible way to enhance the chemical bonding between the fiber and matrix in the hope that it would not effect the fiber tensile strength. Microbond tests were carried out to measure the effect of an ALD aluminum oxide (Al2O3) coating on the fiber/matrix interfacial shear strength, and the fiber tensile strength was measured in order to assess whether this treatment harms the fiber strength. The ultrahigh molecular weight polyethylene (UHMWPE) fibers that were coated by ALD with aluminum oxide (Al2O3) showed a significant increase in the interfacial shear strength without reducing the fibers’ ultimate tensile strength.

scholarly journals Enhanced Interfacial Shear Strength and Critical Energy Release Rate in Single Glass Fiber-Crosslinked Polypropylene Model Microcomposites

Materials ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 2552 ◽  
Author(s):  
Uwe Gohs ◽  
Michael Mueller ◽  
Carsten Zschech ◽  
Serge Zhandarov
Keyword(s):  
Shear Strength ◽  
Electron Beam ◽  
Energy Release Rate ◽  
Glass Fiber ◽  
Release Rate ◽  
Interfacial Shear Strength ◽  
Glass Fibers ◽  
Critical Energy ◽  
Interfacial Shear ◽  
Critical Energy Release Rate

Continuous glass fiber-reinforced polypropylene composites produced by using hybrid yarns show reduced fiber-to-matrix adhesion in comparison to their thermosetting counterparts. Their consolidation involves no curing, and the chemical reactions are limited to the glass fiber surface, the silane coupling agent, and the maleic anhydride-grafted polypropylene. This paper investigates the impact of electron beam crosslinkable toughened polypropylene, alkylene-functionalized single glass fibers, and electron-induced grafting and crosslinking on the local interfacial shear strength and critical energy release rate in single glass fiber polypropylene model microcomposites. A systematic comparison of non-, amino-, alkyl-, and alkylene-functionalized single fibers in virgin, crosslinkable toughened and electron beam crosslinked toughened polypropylene was done in order to study their influence on the local interfacial strength parameters. In comparison to amino-functionalized single glass fibers in polypropylene/maleic anhydride-grafted polypropylene, an enhanced local interfacial shear strength (+20%) and critical energy release rate (+80%) were observed for alkylene-functionalized single glass fibers in electron beam crosslinked toughened polypropylene.

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