U.S. patent application number 11/252377 was filed with the patent office on 2006-05-25 for aluminum oxide ceramics with hydroxyapatite.
Invention is credited to Hans Andersch, Wolfgang Burger, Gert Richter, Herbert Richter.
Application Number | 20060110607 11/252377 |
Document ID | / |
Family ID | 7933740 |
Filed Date | 2006-05-25 |
United States Patent
Application |
20060110607 |
Kind Code |
A1 |
Andersch; Hans ; et
al. |
May 25, 2006 |
Aluminum oxide ceramics with hydroxyapatite
Abstract
The invention relates to a method for producing hydroxyapatite
coated ceramics components. In a first step of the inventive method
the ceramic component is provided with a Ti coating and in a second
step a hydroxyapatite is applied to the Ti coating. The invention
further relates to hydroxyapatite coated ceramic components
produced according to the inventive method.
Inventors: |
Andersch; Hans; (Heiningen,
DE) ; Burger; Wolfgang; (Plochingen, DE) ;
Richter; Herbert; (Kongen, DE) ; Richter; Gert;
(Remchingen, DE) |
Correspondence
Address: |
FULBRIGHT & JAWORSKI, LLP
666 FIFTH AVE
NEW YORK
NY
10103-3198
US
|
Family ID: |
7933740 |
Appl. No.: |
11/252377 |
Filed: |
October 18, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10168414 |
Nov 13, 2002 |
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PCT/EP00/13109 |
Dec 21, 2000 |
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11252377 |
Oct 18, 2005 |
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Current U.S.
Class: |
428/432 ;
427/2.1; 427/248.1; 427/402; 427/421.1; 427/569 |
Current CPC
Class: |
C04B 41/52 20130101;
C23C 14/14 20130101; A61L 27/42 20130101; C04B 35/10 20130101; A61L
27/105 20130101; A61L 27/105 20130101; C04B 41/5133 20130101; C04B
41/4529 20130101; C04B 41/5048 20130101; C04B 41/4527 20130101;
A61L 27/32 20130101; C04B 41/89 20130101; C04B 41/53 20130101; B05D
3/12 20130101; A61L 27/32 20130101; C04B 41/009 20130101; A61L
27/42 20130101; C04B 2111/00836 20130101; A61F 2310/00796 20130101;
A61L 27/105 20130101; A61L 27/32 20130101; C04B 41/009 20130101;
C04B 41/52 20130101; C04B 41/52 20130101 |
Class at
Publication: |
428/432 ;
427/402; 427/002.1; 427/248.1; 427/421.1; 427/569 |
International
Class: |
B32B 17/06 20060101
B32B017/06; H05H 1/24 20060101 H05H001/24 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 21, 1999 |
DE |
199 61 917.4 |
Claims
1-14. (canceled)
15. A method for the manufacture of an hydroxyapatite coated
ceramic component, comprising coating a ceramic component with a
titanium coating comprising at least one of titanium or TiAl6V4
alloy and applying hydroxyapatite to the titanium coating to
produce the hydroxyapatite coated ceramic component, wherein the
titanium coating is from 1 to 5 microns thick.
16. A method according to claim 15, further comprising roughening a
surface of the ceramic component before coating with titanium.
17. A method according to claim 15, wherein said titanium coating
is rough.
18. A method according to claim 15, wherein said titanium coating
is adjusted to a roughness of R.sub.a.apprxeq.40 to 50 .mu.m.
19. A method according to claim 15, wherein said titanium coating
is deposited onto a surface of the ceramic component by a PVD
process.
20. A method according to claim 15, wherein said titanium coating
comprises TiAl6V4 alloy and is applied to said ceramic component by
a PVD process.
21. A method according to claim 15, wherein said titanium coating
is 5 micron thick.
22. A method according to claim 15, wherein said hydroxyapatite is
applied onto the Ti or TiAl6V4 coating by spraying
23. A method according to claim 15, wherein said hydroxyapatite is
applied to the Ti or TiAl6V4 coating by plasma coating.
24. A method according to claim 15, wherein said ceramic component
is an aluminum oxide ceramic.
25. A method according to claim 15, wherein said ceramic component
is for medical use.
26. A method according to claim 15, wherein said ceramic component
is a prosthesis.
27. A method according to claim 15, wherein said titanium coating
is 1 micron thick.
28. A hydroxyapatite coated ceramic component prepared according to
the method of claim 15.
Description
BACKGROUND AND SUMMARY OF THE INVENTION
[0001] The subject of the present invention is a method for the
manufacture of ceramic components coated with hydroxyapatite, as
well as the ceramic components which can be manufactured by this
method.
[0002] It is known that prostheses which have a hydroxyapatite
coating display an especially good ingrowth activity. Care must be
taken, however, to see that the hydroxyapatite coating firmly
adheres to the prosthesis. In the coating of titanium shafts with
hydroxyapatite an especially great strength of adherence can be
achieved when the metal surface is given a roughness of
R.sub.a.apprxeq.40-50 .mu.m.
[0003] The adhesive strength of hydroxyapatite apatite on ceramic
surfaces, especially on Al.sub.2O.sub.3 ceramics, is not sufficient
for the desired use. Thus any direct coating of an aluminum oxide
ceramic with hydroxyapatite, such as would be very advantageous for
the direct fixation of the femur part of a knee prosthesis, is
impossible. Even if the surface roughness is made similar to the
roughness of the titanium shafts, the strength of the adhesion of
hydroxyapatite is not assured. This has been proven in experiments
in which ground and sand-blasted samples were used. In comparison
with titanium materials the surface roughness of ceramic base
materials thus treated is substantially lower. Coating tests with
the standard parameters for titanium shafts resulted in no strength
of adhesion between hydroxyapatite and aluminum oxide ceramic.
Inasmuch as no coating adhered to aluminum oxide bodies under
standard conditions, the spray parameters was also modified in the
plasma coating apparatus. But even the modified process parameters
did not lead to success. The cause of the poor strength of adhesion
was determined to be the differences in roughness between the metal
and the ceramic. A surface roughness of R.sub.a.apprxeq.30 .mu.m
cannot be achieved by conventional abrasive methods.
[0004] Even methods which lead to increased depth of roughness did
not bring the desired success. To produce a greater defined surface
roughness, similar specimens were prepared for laser machining
under various settings. In this manner it was possible to produce a
lasting effect on the surfaces of the Al.sub.2O.sub.3 ceramic.
While in the case of normal grinding a raw depth of no more than 1
.mu.m could be achieved, the laser treatment succeeded in producing
a raw depth of R.sub.a.apprxeq.9 .mu.m. FIG. 3 shows the typical
surface after the laser treatment. The lasered surface of the
aluminum oxide ceramic was then subjected to plasma coating with
hydroxyapatite. For the first time a few placed on this surface
were detected, on which the hydroxyapatite coating could be
detected. Of course, it was not possible even by this preliminary
treatment to apply a continuous coating. FIGS. 4 and 5 show the
surfaces of the lasered and hydroxyapatite (HA) coated
specimens.
[0005] Even though it was possible for the first time to prove the
deposition of hydroxyapatite on the roughened surfaces of the
aluminum oxide ceramic, the strength of adhesion of the coating was
very poor. Quantification of the strength of adhesion was
impossible, as was the preparation of a transverse section; the
coating fell off immediately. Again, when the raw depth was
analyzed it was compared with that of metal materials. With an
R.sub.a of 9 .mu.m the raw depth of the TiAl6V4-1 alloy
(R.sub.a.apprxeq.40 .mu.m) could not be achieved. It was necessary
to refrain from any further roughening of the surface in the
ceramic substrate, since the aluminum oxide ceramic, unless
metallic materials, has an absolute cleavage fracture tendency. If
a "predamage" of 40 .mu.m is induced, this "flaw" can trigger
breakage. Thus, any further increase of the roughness is impossible
from the viewpoint of fracture mechanics.
[0006] The present invention is addressed to the problem of making
available a method by which ceramic components can reliably be
provided with a hydroxyapatite coating.
[0007] The problem to which the invention is addressed has been
solved by a method with the features of the principal claim.
Preferred embodiments are described in the subclaims.
BRIEF DESCRIPTION OF THE FIGURES
[0008] FIG. 1 is an SEM showing a typical surface after laser
treatment.
[0009] FIG. 2 and 3 are SEMs showing the surfaces of the lasered
and hydroxyapatite coated specimens.
[0010] FIGS. 4 and 5 are SEMs showing the transverse section of a
lasered end and hydroxyapatite coated specimens.
[0011] FIG. 6 is an SEM showing the transverse section of a coated
specimen.
[0012] FIGS. 7 and 8 are SEMs showing transverse sections of a
hydroxyapatite layer.
[0013] FIG. 9 shows a typical building of layers in the preparation
of transverse sections.
DETAILED DESCRIPTION
[0014] FIG. 1 shows the typical surface after the laser treatment.
The entire surface of the aluminum oxide ceramic was then subjected
to plasma coating with hydroxyl apatite. For the first time it was
possible to detect on this surface a few spots on which the
hydroxyl apatite coating could be detected. Nevertheless it was not
possible even after this preliminary treatment to apply a
continuous coating. FIGS. 2 and 3 show the surfaces of the lasered
and hydroxyl apatite (HA) coated specimens.
[0015] Surprisingly it was possible according to the invention to
coat a ceramic component, preferably a component made of aluminum
oxide ceramic, with hydroxyapatite if the surface of the ceramic
component is coated with a titanium layer. By the method of the
invention it is surprisingly possible for the first time to deposit
hydroapatic on the surface of a ceramic component, with sufficient
strength of adhesion.
[0016] According to the invention, first ceramic components are
provided with a thin titanium coating, for example by PVD (physical
vapor deposition). According to the invention, the surface of the
ceramic component can be previously roughened,--ground or lasered,
for example. The thickness of the titanium layer was about 1 .mu.m;
a coating 5 .mu.m thick also led to success. FIG. 6 shows the
transverse section of a specimen coated in this manner.
[0017] The hydroxyapatite layer was sprayed onto this intermediate
layer. The transverse section of this built-up coating is
represented in FIGS. 7 and 8 at different enlargements.
[0018] Preferably, before the hydroxyapatite is applied by plasma
coating, for example, the titanium intermediate layer is subjected
also to a sand blasting process to improve adhesion. An especially
high strength of adhesion is achieved if the titanium coating is
given a roughness of R.sub.a.apprxeq.40-50 .mu.m.
[0019] A scratch test on the hydroxyapatite coating confirmed the
outstanding strength of adhesion of the coating. Preparation of a
transverse section was possible without problems. The measurement
of the strength of adhesion was made on five different specimens.
The individual values are summarized in Table 1. TABLE-US-00001
TABLE 1 Strength of adhesion of hydroxyapatite on Al.sub.2O.sub.3
with titanium primer Specimen Force [N] Tension [MPa] 1 718 2.3 2
1203 3.8 3 932 3 4 1490 4.7 5 390 1.2
[0020] From the values obtained by the strength-of-adhesion
measurements it can be seen that tensions are surprisingly achieved
which are in the range of that of hydroxyapatite coatings on
TiAl6V4 alloys.
[0021] According to the invention, it is also possible, instead of
the conventional titanium intermediate coating, an intermediate
coating of the TiAl6V4 alloy can be deposited, for example by the
PVD method.
[0022] FIG. 9 shows the typical building of layers in the
preparation of transverse sections. The corresponding strengths of
adhesion are listed in Table 2. TABLE-US-00002 Specimen Force [N]
Tension [MPa] 1 582 1.9 2 700 2.2 3 400 1.3 4 498 1.6
[0023] A ceramic component in the form of a cylindrical test
specimen was used in the tests. The cylinders, with a diameter of
20 mm and a thickness of 2 mm, were made by the conventional
press-turn manufacture as greenbodies, subjected to hot isostatic
pressure and annealed. The sintered bodies were then machined with
diamond tools to achieve final shape. Other methods for the
manufacture of ceramic components can, of course, also be used.
Used as the material was a known aluminum oxide material, such as
the one known as Biolox.RTM. material, for example.
[0024] With the present invention it is thus for the first time
possible by providing a titanium intermediate coating to deposit
hydroxyapatite directly onto ceramic components. The ceramic
components that can be made by the method of the invention are also
subject matter of the present invention.
[0025] Thus, according to the invention, ceramic components can for
the first time be made, which can be used for medical purposes, for
example as prostheses. Such prostheses display an improved ingrowth
characteristic.
* * * * *