U.S. patent number 3,877,297 [Application Number 05/421,484] was granted by the patent office on 1975-04-15 for process and apparatus for determining the infinitesimal-hardness behaviour of synthetic materials, coatings and ductive materials.
Invention is credited to Kurt Martin Oesterle.
United States Patent |
3,877,297 |
Oesterle |
April 15, 1975 |
Process and apparatus for determining the infinitesimal-hardness
behaviour of synthetic materials, coatings and ductive
materials
Abstract
A process and apparatus for the rapid determination of the
infinitesimal-hardness behaviour of plastic materials, coatings and
ductile materials. The process is characterized in that there is
employed the continual penetration at a narrowly defined location
on a layer of an indentor for the continual recording of the
therewith associated penetration depth, whereby this penetration by
the indentor may take place in a normal or in a particularly formed
atmosphere. In connection therewith, the penetration and,
respectively, the loading sequence must be so controlled, whereby
the sequence of the continually varying loads and the therewith
associated continual penetration values may be digitally recorded
in small incremental steps.
Inventors: |
Oesterle; Kurt Martin (8700
Kusnacht, CH) |
Family
ID: |
4427439 |
Appl.
No.: |
05/421,484 |
Filed: |
December 3, 1973 |
Foreign Application Priority Data
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Dec 4, 1972 [CH] |
|
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17702/72 |
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Current U.S.
Class: |
73/81 |
Current CPC
Class: |
G01N
3/42 (20130101); G01N 2203/0286 (20130101); G01N
2203/0098 (20130101) |
Current International
Class: |
G01N
3/42 (20060101); G01N 3/40 (20060101); G01N
3/02 (20060101); G01N 3/00 (20060101); G01n
003/48 () |
Field of
Search: |
;73/81,85 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Gilu; James J.
Assistant Examiner: Ciarlante; Anthony V.
Attorney, Agent or Firm: Haseltine, Lake & Waters
Claims
What is claimed is:
1. In a process for determining the infinitesimal-hardness
behaviour of plastic materials, in particular coatings and ductile
materials, including penetrating a test material layer with an
indentor in dependence upon a load exerted on the indentor; and
recording the extent of penetration; the improvement comprising:
continually effecting said penetration by said indentor in small
steps at narrowly defined locations on said layer, concurrently and
continually increasing the load on said indentor; operatively
connecting a process calculator and computer to a portion of said
indentor providing measurement values of the depth of penetration
in dependence upon the load exerted on said indentor, said
calculator and computer continuously recording depths of
penetration y in dependence upon loads F exerted on said indentor,
transforming this relationship into F/y-quotients, plotting a curve
through these F/y-quotients in dependence upon loads F and
determining the crossing-point with the F/y-ordinate axis so as to
indicate the value of the Infinitesimal-Hardness-Behaviour IHV.
2. An improvement as claimed in claim 1, said process being
effected under a normal atmospheric environment.
3. An improvement as claimed in claim 1, said process being
effected in a climatized chamber.
4. An improvement as claimed in claim 1, comprising subjecting said
test material to thermal conditioning, cincluding selective heating
and cooling thereof.
5. An improvement as claimed in claim 1, comprising conditioning
said test materials through climatizing preceding the penetration
testing thereof; and imparting additive specialized conditioning to
said test materials.
6. An improvement as claimed in claim 5, said specialized
conditioning comprising mechanical treatment of said test
materials.
7. An improvement as claimed in claim 5, comprising imparting said
specialized conditioning to said test materials through the
intermediary of acid fumes.
8. An improvement as claimed in claim 7, said acid fumes being one
or more inorganic acids selected from the group consisting of HCl,
H.sub.2 SO.sub.4 and HNO.sub.3.
9. An improvement as claimed in claim 7, said acid fumes being one
or more organic acids selected from the group consisting of citrio
acid, lactic acid and chloracetic acid.
10. An improvement as claimed in claim 7, comprising imparting said
specialized conditioning to said test materials through the
intermediary of solvent vapours, such as one or more in
combination, water, alcohol, esters, ethers, acetates, aromatic and
aliphatic carbohydrates.
11. An improvement as claimed in claim 7 comprising imparting said
specialized conditioning to said test materials through aggressive
gases, said gases being one or more gases selected from the group
consisting of SO.sub.2, HCl, HF.
12. An improvement as claimed in claim 7, comprising imparting said
specialized conditioning to said test materials through electrical
and electromagnetic treatment, such as, high-frequency currents,
light beams, infrared light, ultraviolet light, radioactive rays,
and X-ray electron beams.
13. An improvement as claimed in claim 7, comprising concurrently
imparting a combination of specialized conditioning treatments to
said test materials.
14. An improvement as claimed in claim 1, said narrowly defined
location on said layer comprising a single point of initial contact
between said indentor and said testing material layer.
15. An improvement as claimed in claim 1, said indentor comprising
a spherical penetration member.
Description
FIELD OF THE INVENTION
The present invention relates to a process and apparatus for the
rapid determination of the infinitesimal-hardness behaviour (IHV)
of plastic or synthetic materials, coatings and ductile
materials.
The IHV-process, as such, was first made public by the applicant in
1968 in Brussel, Belgium and, concurrently, an illustration of
associated manually controlled apparatus and methods of evaluation.
If, under normal penetration hardness-measurement, F defines the
load under which an indentor, -pyramid-tip, shere, conical point
and the like, penetrates into the upper surface of the material
being tested to a penetration depth y, then these reciprocal
relationships are normally represented by a diagram represented by
the curves in FIG. 1, as discussed in datail hereinbelow. This type
of curve, however, showed itself to be dependent upon the load time
duration, the configuration and outer surface characteristics of
the indentor and, for thin coatings and lacquer layers, additional
dependence upon the thickness of the layer.
In lieu of characterizing the hardness of an outer surface by means
of these curves, it has also been attempted to use the penetration
surface for this purpose, in effect, circular or rectangular, which
is left by the correspondingly shaped indentor after completion of
the penetrating process. Thusly, the Brinell-hardness was expresses
as H = F/A, wherein F designates the load, and A the penetration
surface. However, this method of hardness measurement also
evidenced the disadvantage of the above-mentioned
parameter-dependencies.
The novel aspect of the IHV-process, however, lies in that the
quotient F/y is recorded in dependence on the load F, as set forth
in the curves persuant to FIG. 2, from which there similarly is
obtained a parameter-dependent quotient curve. However, inasmuch as
the crossing point of this curve with the ordinate axis forms a
so-called boundary or limit-value, this particular boundary
transition has been found to be parameter-independent to greatest
possible extend. Consequently, this value has been characterized as
a particularly distinguished value as the "IHV-value", having the
equation
IHV = lim (F/y).sub.F.sub..fwdarw. 0
The foregoing represents an extremely significant value, which is
singular for the material being utilized, with the value being
varied in a characteristic manner through the conditions and
minutest changes experienced by the material from external,
frequently intended, influences. Extensive experiments and
theoretical investigations have indicated that
IHV .about. C .sqroot. E
wherein
C = a finely variable value, dependent upon, the particular
material and condition of the test object; and
E = the modulus of elasticity of the material of the test
object.
The IHV-values thereby also encompass the interactions between, for
example, pigment and plastic material interiorly of heterogeneous
and quasi-homogeneous plastic material-matrices; interactions,
which again lead to further results respecting the structure,
build-up and relationships of the materials. The IHV-value is a
decidedly outer surface value, which is, however, also determined
in a certain degree by the immediate or contiguously adjoining
lower layers. Since plastic material and coating outer surfaces
react quite rapidly in response to external conditions, the
IHV-value also immediately responds to changes in the exterior
conditions of the plastic material, and the like. Such external
conditions may be, for example, those of exterior weathering,
artificial weathering, gas, steam and liquid applications,
electrical, mechanical, magnetic and radiation conditions, and so
forth. Thus, the artificial weathering may be effected in a
suitable climatized chamber, or in a sealed climatized chamber
containing the materials to be tested. The chamber may be heated so
as to provide suitable temperature conditions. The teasting
conditions may also be created through treatment of the materials
with acid fumes, such as of inorganic acids, i.e. HCl, H.sub.2
SO.sub.4, HNO.sub.3, or organic acids such as HCOOH, CH.sub.3 COOH,
ditric acid, lactic acid or chloracetic acid. The fumes or vapors
may also be constituted of water, alcohol, esters, ethers,
acetates, aromatic and aliphatic carbohydrates. Aggressive gases,
such as SO.sub.2, HCl and HF may also be employed.
The electrical influences or effects for conditioning the materials
may comprise high-frequency currents, light beams including
infrared, ultraviolet, radioactive, X-ray and electron beams.
All of the aforementioned conditioning and afflicting elements may
be used individually, collectively, or in various combinations, as
required for the particular evaluation tests.
When a so-treated exterior surface is removed from the conditioning
or treating zone, it builds back mostly quite rapidly, but not
fully reversibly. Thereby it becomes advantageous to create
possibilities which permit the test objects to also be measured
also during the presence of these conditions.
DISCUSSION OF THE PRIOR ART
Heretofore, exterior weathering tests required durations of one to
two years in order to provide definite results. Through the
application of the rapid and sensitively reacting IHV-methods only
hours, days or a few weeks are required therefor. In addition, it
is not necessary to apply falsified elevated conditions which, for
example, are impressed on the probes by means of the
Weather-o-meter.
For reception of the measuring values leading to the IHV-value,
heretofore there have been employed usual or known
microhardness-indentation measuring apparatus such as, for example,
the Wallace-Indentation-Tester, or the ICI-apparatus. The process
entailed that a Vickers-pyramid subjected to variable loads was
pressed into the plastic material being tested for a freely
selected but constant time period, and in which the particular and
time-constant penetration depth was measured or registered in
dependence upon the particular load. However, from penetration to
penetration, the test member had to be displaced for a minutely
small distance, so as to avoid erroneous measurements caused by the
previous measurement of the particular location. The predetermined
loads and the thereby obtained penetration depth values were
divided by each other, and the quotient F/y plotted on a Cartesian
coordinate graph as functions of the loads F. The extrapolation of
the limit-value F .fwdarw. O resulted by means of a regression
curve through the quotient values F/y. The crossing point of the
regression curve with the F/y -ordinates axis then provided the
IHV-value.
SUMMARY OF THE INVENTION
The present invention eliminates the disadvantages encountered in
the described prior art methods with numerous "manually effected"
steps through improvement and acceleration thereof, while requiring
a completely new concept for the obtention of the IHV-value.
Basically it must thereby be determined that there is provided a
consistency in the values, which afford a new limit-transition
toward the IHV-value. The inventive process is thereby
characterized, in that there is employed the continual penetration
at a narrowly defined location of an indentor for the continual
recording of the therewith associated penetration depth, whereby
this penetration by the indentor may take place in a normal or in a
particularly formed atmosphere. In connection therewith, the
penetration and, respectively, the loading sequence must be so
controlled, whereby the sequence of the continually varying loads
and the therewith associated continual penetration values may be
digitally recorded in small incremental steps.
BRIEF DESCRIPTION OF THE DRAWINGS
Reference may now be had to the following detailed description of
the invention, taken in conjunction with the accompanying drawings,
in which:
FIG. 1 is a graphical illustration showing the plot of load with
respect to penetration depth for two coating thicknesses for a
prior art penetration measurement;
FIG. 2 is a graphical illustration similar to FIG. 1 utilizing the
IHV-process according to the present invention; and
FIG. 3 is a schematic view of an apparatus for effecting the
IHV-process according to the present invention.
DETAILED DESCRIPTION
Referring to the drawings, the apparatus disclosed therein
facilitates the application of the method by means of two
alternatives:
Alternative (a):
The penetrating sequence of the indentor is effected without
interruption at a continually increasing load, and the therewith
associated penetration depths are thereby continuously digitally
recorded and evaluated. A family of new curves (F/y, --F) is thus
obtained which, in comparison with the curves from the previous
methods, lies somewhat more elevated, but which must lead, on the
basis of mathematical boundary transition concepts, to the same
IHV-value. Such a recording with rapidly changing values is
unthinkable for a manual peration, and positively retards the
automation.
In order to effect the inventive concept, an apparatus constructed
in accordance with the principle of FIG. 3 may be employed. IN the
drawing, 1 defines the support for a probe 1a, 2 defines the
indentor, 3 and 4 the control system for the indentor, which may be
either electrical or mechanically and pneumatically operated, 4 and
5 comprise the recording means for the penetration depth of the
indentor 2. The load values and the penetration depth values are
amplified by, respectively, elements 6 and 8, and recorded through
component 9, and from which there may be ascertained the balancing
parabola and the crossing point with the F/y axis in a computerized
manner. Component 7 symbolically illustrates the
Zero-position-adjustment installation for the indentor, and
similarly component 10 symbolically illustrates the power supply
circuit for the apparatus.
Alternative (b):
This alternative is particularly suitable for application to
materials having a low modulus of elasticity. In this instance, a
method must be sought in which the penetrating process is braked,
but will nevertheless still lead to a measurable limit-value. This
may be attained in that there may be placed in opposition to the
alternative a of steering the load of the penetrating indentor a
larger continuous operation, which is to be handled in the
material. This may be effected by constructing the indentor as a
wheel having conically ground periphery, so that the object to be
tested is moved in a translatory manner below this loaded wheel.
The wheel may be formed as a starwheel, having peripheral
wedge-shaped segments. In accordance with the type of material,
F/y-- F curves are obtained which lie higher, but occasionally also
lower, than the values obtained through the Alternative (a). The
limit-value must coincide, however, when employing the same
material for Alternatives (a) and (b), again due to the limiting
requirements excluding boundary transition. Above all, the
apparatus here becomes considerably complicated, since for the
Alternative (a), there is still added the translation of
Alternative (b).
While there has been shown what is considered to be the preferred
embodiment of the invention, it will be obvious that modifications
may be made which come within the scope of the disclosure of the
specification.
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