橡胶与金属粘结件的测试与分析

kennygu · 发表于 2009-3-25 21:35:19

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Testing and analysis of rubber-to-metal bonded parts.

The robust nature of rubber-to-metal bonded parts qualifies them for applications in critical systems with hostile environmentsSee: operational environment.
..... Click the link for more information.. If a part fails, it's imperative to determine the root cause of the failure. The constituents of rubber compounds make analysis difficult using traditional methods such as reflectants Fourier TransformFourier transform

In mathematical analysis, an integral transform useful in solving certain types of partial differential equations. A function's Fourier transform is derived by integrating the product of the function and a kernel function (an exponential function raised to
..... Click the link for more information. Infrared Spectrometer spectrometer

Device for detecting and analyzing wavelengths of electromagnetic radiation, commonly used for molecular spectroscopy; more broadly, any of various instruments in which an emission (as of electromagnetic radiation or particles) is spread out according to some  (FTIR FTIR Fourier Transform Infrared (spectroscopy)
FTIR Frustrated Total Internal Reflection
FTIR Fourier Transfer Ir ) or energy dispersive dispersive /dis·per·sive/ (-per´siv)
1. tending to become dispersed.

2. promoting dispersion.  x-ray (EDS (Electronic Data Systems, Plano, TX, www.eds.com) Founded in 1962 by H. Ross Perot (independent candidate for the President of the U.S. in 1992), EDS is the largest outsourcing and data processing services organization in the country. ). Analysis of the system is often more difficult when failure occurs at the adhesive bond interface. The author, using x-ray photon scattering spectroscophy (XPS (1) See XML Paper Specification.

(2) A brand name for certain models of Inspiron laptops from Dell. ) and an ISI ISI International Sensitivity Index, see there  SX-40 scanning electron microscopescan·ning electron microscope
n. Abbr. SEM
An electron microscope that forms a three-dimensional image on a cathode-ray tube by moving a beam of focused electrons across an object and reading both the electrons scattered by the object and
..... Click the link for more information. (SEM) in his analysis, was able to deduce de·duce
tr.v. de·duced, de·duc·ing, de·duc·es
1. To reach (a conclusion) by reasoning.

2. To infer from a general principle; reason deductively:  the most likely cause of failure to be premature crosslinking of the adhesive. By eliminating other possible causes of unbond, such as contamination, a more robust manufacturing process can be developed.

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Carbon black filled rubber parts may challenge many analytical methods because the compounded rubber may include up to twenty individual ingredients. Often, after mixing, it is difficult to extract ingredients from the polymer base due to their interactions with other ingredients such as carbon black.

Analysis of extracted ingredients may give erroneous results due to contamination by other ingredients from the compound. The carbon black components in the blend often interfere with spectural analysis methods because carbon black tends to absorb spectural frequencies, such as infrared.

Testing of bonded rubber-to-metal parts amplifies the problems two-fold. The bonding adhesive is also a multi-component polymericpolymeric /poly·mer·ic/ (pol?i-mer´ik) exhibiting the characteristics of a polymer.
--------------------------------------------------------------------------------

pol·y·mer·ic
adj.
1. Having the properties of a polymer.

2.
..... Click the link for more information. blend, much like the rubber. Also involved are contaminants associated with the substrate. For example, a stamped steel insert may be contaminated contaminated,
v 1. made radioactive by the addition of small quantities of radioactive material.
2. made contaminated by adding infective or radiographic materials.
3. an infective surface or object.  with hydrocarbons. If the metal is porous, oil may bleedPrinting at the very edge of the paper. Many laser printers, including all LaserJets up to the 11x17" 4V, cannot print to the very edge, leaving a border of approximately 1/4". In commercial printing, bleeding is generally more expensive, because wider paper is often used, which is later
..... Click the link for more information. out of the metal grain over time and undermine a bond system. Or, if the oil is present initially, it may prevent adhesive wet-out, thus inhibiting adhesion to the substrate.

Traditional analysis lacking?

Some techniques such as reflectants FTIR and EDS would not be adequate for testing rubber bonded to metal. EDS, using a windowless system, does not have sufficient resolution to detect lower weight elements. Typically, with a windowless system, resolution begins to soften around sodium.

Techniques such as FTIR are subject to error due to occlusion occlusion /oc·clu·sion/ (o-kloo´zhun)
1. obstruction.

2. the trapping of a liquid or gas within cavities in a solid or on its surface.

3.  of peaks by stronger signals. Both of these methods tend to penetrate the samples to a degree that an accurate compositional analysis of the surface cannot be obtained. This information and data are most critical in bond failure analysis.

XPS, SEM most definitive

To gain the most definitive picture of failed bonded surfaces, SEM and x-ray photon scattering methods have proven the most valuable.

Using SEM techniques, an excellent picture of the failed surface may be obtained. With bonded rubber compounds, often both the adhesive and the rubber are black, making it difficult to determine where the rubber begins and the adhesive ends. Since SEM images are produced by bouncing electrons off a surface, at a given angle to a detector, artifacts artifacts

see specimen artifacts.  as small as one micron are detectable.

This is sufficient to detect differences between adhesives and rubber, or detect other materials on the surface of a part. This information is crucial in determining how a part failed. A good visual representation of the surface can help determine whether the bond failed adhesively or cohesively. It can also be used to determine to what degree a part may have been bonded before it failed.

XPS, or ESCA ESCA Electron Spectroscopy for Chemical Analysis
ESCA Escaflowne (anime series)
ESCA European Speech Communication Association
ESCA Escuela Superior de Comercio y Administración (México) , is an excellent method for determining chemical composition of a surface. This method penetrates the surface of the sample to a depth of only 50 microns. XPS measures the binding energies of the atoms present on the surface, yielding a very distinctive signature of the atomic species present. XPS is sensitive enough to generate signals that provide both a quantitative and qualitative picture of the surface composition over a wide elemental range. Computer analysis techniques convert these signals to atomic percentages to allow reconstruction of the various materials present.

Case study example

The following case study analyzes black rubber bonded to a steel part. The part was exposed to a hostile environment (hydrocarbon fluids at 150 [degrees] C) for a relatively short period of time before failure occurred. Parts of this type are expected to last approximately eight years; this part failed in under six months.

Initial visual analysis indicated failure primarily in an adhesive mode. However, no apparent cause of the failure was easily identifiable. Gaining a clear understanding of the cause of the adhesive failure at this point was difficult because the part was saturated with hydrocarbon oil.

An ISI SX-40 scanning electron microscope was used to analyze the mating failed surfaces and a cross section of the bonded surface. The photographs in figures 1 and 2 show the failed surfaces magnified up to 150 times. These pictures show surfaces were relatively smooth and interacted very little. What appeared to be pulled-out material was present on one surface with fishers on the opposite face. This would indicate the part was partially bonded before it failed.

The cross section (figure 3) of the remaining bonded area indicated that under normal conditions
This article is about the philosophical argument; for normal conditions in the sense of standards see the corresponding articles, e.g. Standard conditions for temperature and pressure., the adhesive could not be distinguished from the rubber at a magnification Magnification

A measure of the effectiveness of an optical system in enlarging or reducing an image. For an optical system that forms a real image, such a measure is the lateral magnification m  of 45 times. This would indicate a high degree of commingling Combining things into one body.

The term commingling is most often applied to funds or assets. When a fiduciary, a person entrusted with the management of funds other than his or her own in trust, mixes trust money with that of others, the fiduciary is commingling  is necessary between rubber and adhesive to achieve a good bond.

At this point the unbond was believed to be caused by an overbake of the adhesive. In this situation, the poor bond is due to premature crosslinking of the adhesive prior to the application of rubber. The crosslinking of the adhesive causes mechanisms for adhesion to be compromised and inhibits physical interaction.

To confirm this, we subjected both a control part, with bond failure due to adhesive over bake, and the failed part to analysis by XPS. Only failed mating surfaces were examined by this method. Typical areas scanned by this method were 1 mm x 3 mm. It is not necessary to neutralize neutralize

to render neutral.  with the electron gun A device that creates a fine beam of electrons that is focused on a phosphor screen in a CRT.  due to only minimal charging effects. Only a single sample. was tested for each condition.

Samples were scanned in a region between 0 and 1,100 eV. Multiplex See multiplexing.  scanning of all significant peaks seen in the survey was accomplished. Binding energies associated with all observed photopeaks were referenced to the values for C-C/C-H hydrocarbon species at 284.6 eV. Values for atomic concentrations were determined using PHI phi
n.
Symbol  The 21st letter of the Greek alphabet.

--------------------------------------------------------------------------------
PHI,
n See health information, protected.  software version 4.0. Atomic concentrations were determined using the formulation: Atomic % for element X = Ix

Sx Tx

n Ii

[epsilon] Si Ti

i = I

I = photopeak area S = sensitivity factor T = total acquisition time n = number of photopeaks considered

The XPS analysis of the mating surfaces of the defective part (tables 1 and 2) showed the surfaces to be very similar in elemental composition. Values from the failed part, when compared to the control pan (tables 3 and 4), indicated the hydrocarbon fluid did not affect the analysis. This is most likely because the high vacuum, necessary in this testing technique, removed the hydrocarbon fluid from the surface.

   Table 1 - XPS analysis of failed part,
      rubber side of failed area

Element       Area Sensitivity Concentration

      (cts-eV/s)       factor          (%)

C1s          45306       0.296          73.36
O1s          18461       0.711          13.46
N1s          313       0.477          0.34
Si2p          3843       0.339          5.88
Ca2p          1316       1.833          0.37
P2p          342       0.486          0.36
S2p          293       0.666          0.23
Al2p             0       0.234          0.00

   Table 2 - XPS analysis of failed part,
   adhesive/metal side of failed area

Element       Area Sensitivity Concentration

      (cts-eV/s)       factor          (%)

C1s          43017       0.296          73.96
O1s          25671       0.711          18.37
N1s          702       0.477          0.75
Si2p          3436       0.339          5.16
Ca2p          2482       1.833          0.69
P2p          559       0.486          0.59
S2p          570       0.666          0.44
Al2p          23       0.234          0.05

   Table 3 - simulated failure unbond area,
               rubber side

Element       Area Sensitivity Concentration

      (cts-eV/s)       factor          (%)

C1s          40822       0.296          73.29
O1s          24327       0.711          18.18
N1s          594       0.477          0.66
Si2p          4297       0.339          6.74
Ca2p          1320       1.833          0.38
P2p          238       0.486          0.26
S2p          161       0.666          0.13
Al2p          92       0.234          0.21
F1s          287       1.000          0.15

   Table 4 - simulated failure unbond area,
            adhesive/metal side

Element       Area Sensitivity Concentration

      (cts-eV/s)       factor          (%)

C1s          44106       0.296          72.63
O1s          29689       0.711          20.35
N1s          718       0.477          0.73
Si2p          4155       0.339          5.97
Ca2p          673       1.833          0.18
P2p             77       0.486          0.08
S2p             71       0.666          0.05
Al2p             3       0.234          0.01

The trace elements Trace elements
A group of elements that are present in the human body in very small amounts but are nonetheless important to good health. They include chromium, copper, cobalt, iodine, iron, selenium, and zinc. Trace elements are also called micronutrients.  present in analysis of both surfaces of both parts support the conclusion that the parts failed by the same mechanism. Test results support the idea that both samples failed in a boundary layer boundary layer

In fluid mechanics, a thin layer of flowing gas or liquid in contact with a surface (e.g., of an airplane wing or the inside of a pipe). The fluid in the boundary layer is subjected to shear forces.  between the rubber and the adhesive. Trace elements, known not to be native to the rubber compound, indicate the source to be the adhesive.

This was further supported by the SEM photographs that showed pull-out in the adhesive layer.

Conclusions

From the presence of adhesive components on all mating surfaces tested, we can effectively eliminate contamination as the cause of the unbond. The presence of the adhesive and the pulled-out material present on the failed part would indicate the part may have been weakly bonded. Finally, the evident lack of adhesive and rubber interspersion in·ter·sperse
tr.v. in·ter·spersed, in·ter·spers·ing, in·ter·spers·es
1. To distribute among other things at intervals:  would indicate one or both components had achieved sufficient viscosity to resist flow. The combined evidence tends to support our initial observation that all adhesive had prematurely crosslinked. This data will allow us to act correctly on the cause and help produce a more robust part and process.

James Jacks has been with Acadia Polymers for the past four years. His job responsibilities have included materials development and analysis. He has been associated with the Virginia Polytechnic Univ. through a grant program he coordinates. The primary focus of the grant has been the study of materials and bond integrity in application environments.
COPYRIGHT 1996 Lippincott & Peto, Inc.
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 1996, Gale Group. All rights reserved. Gale Group is a Thomson Corporation Company.

lsgcxl · 发表于 2009-3-25 23:06:41

呵呵，从那搞的资料，拷下来慢慢研究

wangansi · 发表于 2009-3-27 18:54:31

为啥又是英文的呢？？？

kennygu · 发表于 2009-3-27 19:28:47

网上下载的，只要看懂标题就可以了

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