Int Poster J Dent Oral Med 2000, Vol 2 No 1, Poster 33
Experimental studies on surface treatment of Titanium by new blasting techniques
Authors: Ulrike Lenz, Edwin Lenz, Gerhard Raser
Dept. of Prosthetic Dentistry and Dental Material Research, Friedrich Schiller
University Jena, Germany
23rd Annual Conference of the Prosthodontic Association (EPA)
Quintessenz Poster Prize 1999
Surface conditions of Titanium castings are influenced by interface reactions
between Titanium and the investment material. There are the sinterfusing
and uptake of elements from the investment material and formation of an oxygen
rich surface layer (µ-case). The usual surface
treatment is sandblasting with corundum 250µm. It´s characterised
by strong surface roughening, plastic deformation, microstructural defects
and impaction of blasting grains. That's why there is a new technique of
surface treatment developed so called micro-finishing. An abrasive and spherical
medium are used in this technique.
|Fig.1: casted Titanium, cleaned in an
|Fig.2: sandblasted Titanium (corundum
||Fig.3: abrasive Medium 1 (M1)
||fig.4: spherical Medium 2 (M2)
The aim of the following investigation was the experimental evaluation of
this micro-blasting method, using the abrasive and spherical medium separate
and in combination.
Material and Methods
Casted samples of Titanium (grade 1; Biotan®) were used in
following initial surface conditions:
- casted and cleaned in an ultrasonic bath
- wett ground on SiC-paper, grit size 220,600,1200
The samples were finished by using the abrasive and spherical medium, separate
and in combination. The surface conditions were characterised by using:
- light- and scanning electron microscopy (SEM)
- light microscopically investigation on metallographic transverse sections
- analysis of the profile graphs (RZD,Sm)
Micro-finishing of surfaces in cast condition
1. Surface condition after using the fine-grain abrasive medium (M1):
Sinter-fused particles are removed and there's a surface roughening, but
lower compared with usual sandblasting, the oxygen rich surface layer is
reduced and there are no plastic deformations or microstructural defects.
2. Surface condition after using the spherical blasting medium (M2): The
M2 effects a surface levelling by plastic deformation (ball imprints); the
oxygen rich surface layer is low reduced.
3. Surface condition after using medium 1 and 2 in combination: There is
a cleaning and smoothening effect: the surface roughening by the abrasive
blasting is levelled by micro-peening, the
µ-case is clearly reduced, the surface is
smoothed and there are no microstructural defects.
|Fig.5: sandblasted Titanium (corundum
||Fig.6: casted Titanium, finished by using M1
||Fig.7: casted Titanium, finished by using M2
||Fig.8 casted Titanium, finished by using M1+M2
||Fig.9 analysis of the profile graphs
Micro-finishing of ground surfaces
1. Ground surface with SiC220 before micro-finishing shows a removed
µ-case, small deformation range and roughened
surface. After using M2 there are wide deformation ranges (slip bands up
to 30µm) and impactions of blasting grains.
2. Ground surface with SiC1200 before micro-finishing shows slight surface
roughening and minimum deformation range. After using M2 there are wide
deformation ranges (slip band up to 25µm) and impactions of blasting
3. The evaluation of the profile graphs demonstrates a levelling affect of
grinding and fine grinding before micro-finishing (roughness depths between
1,1 and 0,9 µm). The micro-finishing effects an increase of roughness
depths up to 2,4 µm.
|fig.10: ground surface
|Fig.11: ground surface, finished with M1+ M2
||Fig.12: fine ground surface (SiC 1200)
||Fig.13: fine ground surface, finished with M2
Discussion and Conclusions
1. The abrasive micro-blasting of Titanium castings removes surface near
layers. In contrast to the usual corundum blasting the method shows an levelling
effect. Microstructural defects are diminished.
2. Micro-peening in combination with foregoing abrasive micro-blasting effects
a further levelling and compaction of the surface.
3. Abrasive micro-blasting and micro-peening of fine-ground surfaces is of
4. The micro-finishing technique enables a rationalization of surface finishing
and improvement of surface quality of Titanium castings.
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Oberflächenbearbeitung von gegossenem Titan für Kronen und
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zur Oberflächenbeschaffenheit von gegossenem Titan. Dtsch. Zahnärztl.
Z.1992, 47, 505-507
- Swinkels, H.: Das Strahlen von Metalloberflächen.
Metalloberfläche,1986, 40, 315-316
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- Dreher, M.: Massfinishing. Metalloberfläche,1995, 49, 96-98
- Rüsterholz, R.: Shot-peening. Verformen und Vergüten in
höchster Präzision. Metalloberfläche, 1991,45, 269-271
- Lenz, E.: New methods of surface finishing of Titanium. 4th International
Symposium of Titanium in Dentistry. Abstracts, Geneva 1998
RZD - average depth of roughness
Sm - medium distance of roughness peaks
This Poster was submitted on 28.02.00 by
Klinikum der Friedrich-Schiller-Universität Jena
Zentrum für Zahn-, Mund- und Kieferheilkunde
Poliklinik für Zahnärztliche Prothetik und Werkstoffkunde
An der Alten Post 4
D - 07740 Jena