**2.1 Submicrocrystalline sintered corundum grains**

Submicrocrystalline sintered corundum grains is a new generation of alfa type aluminum oxide with ultradispersive structure, which was obtained by transformation of sol – gel

another big, commercial group of products that are applied in the clinical practice (Biolox, Synatite, Endobone, Neobone, Cerabone) (Jaegermann Z., Ślósarczyk A. 2007, Jaegermann

The newest trend in the regenerative medicine area is tissue engineering, which aimes to

Biocompatible alumina composites are a new generation of ceramic glass materials used in tissue engineering (Jaegermann Z. 2005, Szarska S., et al, 2008 Staniewicz – Brudnik B. et al, 2010). Biomaterials substrates (inorganic, polymeric, hybrid) are two – or three dimensional scaffold, which inhabits the cells (eg fibroblasts) by growing them in vitro, and then the resulting product material and cell is implanted in place of the defect (Chen Q. Z., et al 2008, Brovarone C., Verne E. 2006). The main task of such a scaffold is the physical support for cells and the control of their proliferation, differentiation and morphogenesis (Sachlos E.,

The basic criteria that should have the substrates (Teramoto H., et al, 2005, Staniewicz – Brudnik B., Lekka M., Bączek E. 2010, Czechowska J., Ślósarczyk A. 2011) are formulated as

• the substrate should contain open pores that connect to each other about the right size

• they should have appropriate chemical properties (bioactivity, non – toxic) to promote attachment of cells to substrates, their differentiation and multiplication, mechanical properties (tensile strength, torsion, hardness, Young's modulus) close to the natural

• they should be made of materials with controlled biodegradability (biosorption), so that

Taking into considerations all these above requirements the substrates were synthesized, which are biocompatible corundum glass system composites. Biocomposites by combining the characteristics of these materials (Al203, glass) allow to achieve unique properties such as high mechanical strength, crack resistance, high biocompatibility and bioactivity (Hee – Gon

The aim of our work is to obtain corundum- glass biocomposites – meeting the above

The usefulness verification of new substrates was based on short -term cultures of fibroblast human skin of CCL 110 line from Prochem company and mouse preosteoblasts MC3T3 – E1

**2. The effect of mechanochemical treatment of submicrocrystalline sintered** 

Submicrocrystalline sintered corundum grains is a new generation of alfa type aluminum oxide with ultradispersive structure, which was obtained by transformation of sol – gel

**corundum grains on their certain physical – Mechanical properties** 

obtain medicines and decrease number of complications.

to inclusion of cells, then tissues and their vascularity;

tissue could be replaced after a specified time basis ; • do not cause adverse reactions (including allergic)

B., et al, 2008, Abo – Mosallam H.A., et al, 2009).

**2.1 Submicrocrystalline sintered corundum grains** 

Subclone14 from the same company.

• they should be easily manufactured in various shapes and sizes.

criteria, obtained in a simple, inexpensive and energy efficient way.

Z., et al ,2006).

Czernuszka J. T. 2003).

materials;

follows:

process of aluminum oxide by using Mg0, L2O3, Nd2O3, Y2O3 as modificators. Abrasive grains consist of Al2O3 plates about 0.5 – 1 µm joint by needle bridge of MgLaAl11O19 spinel type. Submicrocrystalline sintered corundum grains have in comparison to conventional corundum materials higher strength (90 MPa, conventional 85 MPa), hardness (20 – 22,5 GPa, conventional 18,5 – 21 GPa) with simultenous increase of fracture toughness. Commercial names of these materials are cubitron, Seeded Gel and Blue Sapphire (Niżankowski Cz. 2002, Markul J. 2008).

The submicrocrystalline sintered corundum grains about 150 granulation (125-150 µm) have microhardness of 21.5 Gpa. They were milled for 10, 15, 20, 25 and 30 hours in the planetary mill Pulverisette 6 type produced by Fritsch Company, in the agate chamber with agate balls in the ethanol addition as a slide agent. The grains samples were removed from the chamber after determined times (10, 15, 20, 25, 30 hours) and taken for the further research procedure. The X – ray research works were conducted on the PW 1710 X – ray diffractometer with cobalt lamp at the range of 2ʘ angle from 20o – 90o. The phase identification and calculation of percentage contents and structure parameters were done using EVA program by Brucker Company.

Fig. 1. The X – ray diffraction images of the samples before and after milling for 10, 15, 25, 30 hours.

Basing on this this research in the initial samples of submicrocrystalline sintered corundum the following phases were identified:

α – Al2O3 with romboedric structure kappa – Al2O3 with orthoromboedrical structure δ – Al2O3 with orthorombic structure non – stoichiometric (spinel) compound – (Mg 0,03 Al 0,35) (Al 1,68 Mg 0,30) O4 with cubic structure.

Biocompatible Ceramic – Glass Composite –

15, 20, 25, 30 hours.

SG – 10 hours – 20 – 1 µm SG – 15 hours – 10 – 1 µm SG – 20 hours – 8 – 1 µm SG – 25 hours – 6 – 1 µm SG – 30 hours – 6 – 1 µm.

SG – 10 hours – 23,6 % SG – 15 hours – 29,0 % SG – 20 hours – 35,7 % SG – 25 hours – 38,9 % SG – 30 hours – 38,9 %.

using ultrasonic method.

and 3.4 m2/g respectively.

size with following percentage contents:

Manufacturing and Selected Physical – Mechanical Properties 231

Fig. 3. Cumulative curves of submicrocrystalline sintered corundum grains after milling for

The second population of grains was distinguished on the diagrams that had about 1 µm

The above data indicate that the thickest grains are complementary milled and consequently the contents of ultrafine particles increases. For samples milled for 25 and 30 hours no significant differences in the grains compositions were observed in the entire measuring range. This can be explained by the formation of grains agglomerates, difficult to break even

The specific surface area of samples was determined by SBET physical adsorption of nitrogen at temperatures of liquid nitrogen from the equation Braunaura – Emmett – Teller. For calculations based on the data from the adsorption isotherms the relative pressure at the range p/p0 0.06 – 0.10 were used. Measurements of specific surface area SBET expressed in m2/g showed the prolonged milling of samples of submicrocrystalline sintered corundum caused a systematic increase in the specific surface area (from 0.1 m2/g for the initial sample to 16.4 m2/g for the sample milled for 30 hours). The greatest effect was achieved after 10 hours milling in relation to the initial sample and after 30 hours of milling in relation to the sample milled for 25 hours and values were 6.4 m2/g

In the milled samples low – temperature quartz (SiO2) appeared, coming from the used agate balls during the milling process.

The contents of α – Al2O3 phase decreased in a benefit of kappa – Al2O3, phase, contents of δ – Al2O3 was on the same level at different parameters of crystallographic lattice. Lattice parameters of spinel decreased.


Table 1. Lattice parameters of individual phases of submicrocrystalline sintered corundum determined from X – ray measurement.

The grains composition measurement were done using Sedigraph 5100 X – ray analyzer (Micrometrics Company). Suspensions from research samples were prepared using solution of distillated water and 0,5% sodium pyrophosphate as a sediment liquid. Grain composition was determined in the range of 100 to 0,2 µm. The measurement results are shown as the cumulative and populative curves in Fig. 2 and 3 respectively.

Fig. 2. Populative curves of submicrocrystalline sintered corundum grains after milling for 15,20,25,30 hours.

Fig. 3. Cumulative curves of submicrocrystalline sintered corundum grains after milling for 15, 20, 25, 30 hours.

SG – 10 hours – 20 – 1 µm SG – 15 hours – 10 – 1 µm SG – 20 hours – 8 – 1 µm SG – 25 hours – 6 – 1 µm SG – 30 hours – 6 – 1 µm.

230 Sintering of Ceramics – New Emerging Techniques

In the milled samples low – temperature quartz (SiO2) appeared, coming from the used

The contents of α – Al2O3 phase decreased in a benefit of kappa – Al2O3, phase, contents of δ – Al2O3 was on the same level at different parameters of crystallographic lattice. Lattice

Table 1. Lattice parameters of individual phases of submicrocrystalline sintered corundum

The grains composition measurement were done using Sedigraph 5100 X – ray analyzer (Micrometrics Company). Suspensions from research samples were prepared using solution of distillated water and 0,5% sodium pyrophosphate as a sediment liquid. Grain composition was determined in the range of 100 to 0,2 µm. The measurement results are

Fig. 2. Populative curves of submicrocrystalline sintered corundum grains after milling for

shown as the cumulative and populative curves in Fig. 2 and 3 respectively.

agate balls during the milling process.

determined from X – ray measurement.

15,20,25,30 hours.

parameters of spinel decreased.

The second population of grains was distinguished on the diagrams that had about 1 µm size with following percentage contents:

SG – 10 hours – 23,6 % SG – 15 hours – 29,0 % SG – 20 hours – 35,7 % SG – 25 hours – 38,9 % SG – 30 hours – 38,9 %.

The above data indicate that the thickest grains are complementary milled and consequently the contents of ultrafine particles increases. For samples milled for 25 and 30 hours no significant differences in the grains compositions were observed in the entire measuring range. This can be explained by the formation of grains agglomerates, difficult to break even using ultrasonic method.

The specific surface area of samples was determined by SBET physical adsorption of nitrogen at temperatures of liquid nitrogen from the equation Braunaura – Emmett – Teller. For calculations based on the data from the adsorption isotherms the relative pressure at the range p/p0 0.06 – 0.10 were used. Measurements of specific surface area SBET expressed in m2/g showed the prolonged milling of samples of submicrocrystalline sintered corundum caused a systematic increase in the specific surface area (from 0.1 m2/g for the initial sample to 16.4 m2/g for the sample milled for 30 hours). The greatest effect was achieved after 10 hours milling in relation to the initial sample and after 30 hours of milling in relation to the sample milled for 25 hours and values were 6.4 m2/g and 3.4 m2/g respectively.

Biocompatible Ceramic – Glass Composite –

b. after 15 hours of milling (2500x magn.) c. after 20 hours of milling (2500x magn.) d. after 30 hours of milling (2500x magn.)

**2.2 Glass of Ca0 – Si02 – P205 – Na20 system** 

13500C by fritting method. Initial materials were:

Calcium carbonate – analytically pure Sodium phosphate – analytically pure

sodium carbonate – analytically pure.

Fig. 5. Glass FB3 system after fritting process.

Silicon dioxide – pure

corundum grains.

of phosphorus.

a. before milling (100x magn.)

Manufacturing and Selected Physical – Mechanical Properties 233

Glass calcium – silicate – phosphate from the system Ca0 – Si02 – P205 – Na20 was obtained at

Three frits were obtained from completely transparent with bluish aquamarine to milky opaque amber colour. Frits were milled in the planetary mill Pulverisette 6 type (Fritsch Company), in the agate chamber with agate balls by 5, 10, 15 and 20 hours with the addition of distilled water. Samples were removed after a certain time subjecting them to further test procedure. A similar procedure was used as in the case of submicrocrystalline sintered

The resulting glass was subjected to chemical analysis on the spectrometer ARL Advant'XP by X – ray fluorescence spectral method. The results of oxide glass compositions were very closed to the calculated theoretically composition, taking into account 10% of the volatility

Observations of the glassy frits using the scanning electron microscope revealed the presence of elongated grains, irregularly shaped with sharply outlined edges. After

prolonged milling a few large grains and clusters of small grains were visible.


Table 2. Granulometric analysis of grains (percentage of the fraction below).

Microscopic observations were performed on scanning electron microscope JSM 6460 LV JEOL Company in the range of low and high vacuum, at 20 kV accelerating voltage. SEM and COMPO images were observed at 100x, 400x, 1000x and 2500x magnifications. In these images elongated, irregular grains with sharp edges were present. In the samples milled 10, 15, 20 hours a few large grains and the increased amount of fine grains was observed. In the sample milled for 30 hours cluster of agglomerates appeared.

Fig. 4. SEM image of submicrocrystalline sintered corundum grains:

a. before milling (100x magn.)

232 Sintering of Ceramics – New Emerging Techniques

on below SG-10 SG-15 SG-20 SG-25 SG-30 40 µm 99.4 100.0 100.0 100.0 100.0 20 µm 95.8 99.3 99.0 97.6 97.2 10 µm 81.7 93.0 97.9 94.0 91.6 5 µm 59.6 71.2 85.0 83.0 79.5 2 µm 34.7 42.3 52.3 53.7 52.1 1 µm 23.6 29.0 35.7 38.9 38.6 0.5 µm 14.8 18.3 22.6 26.9 27.7 0.2 µm 6.1 7.6 10.3 13.1 13.5 **Mediane,** µm **3.70 2.68 1.85 1.72 1.72** 

Microscopic observations were performed on scanning electron microscope JSM 6460 LV JEOL Company in the range of low and high vacuum, at 20 kV accelerating voltage. SEM and COMPO images were observed at 100x, 400x, 1000x and 2500x magnifications. In these images elongated, irregular grains with sharp edges were present. In the samples milled 10, 15, 20 hours a few large grains and the increased amount of fine grains was observed. In the

(a) (b)

(c) (d)

Fig. 4. SEM image of submicrocrystalline sintered corundum grains:

Table 2. Granulometric analysis of grains (percentage of the fraction below).

sample milled for 30 hours cluster of agglomerates appeared.

Sample/fracti

