Sintering behavior and thermal expansion of zirconia–titanium composites
Sintering behavior and thermal expansion of zirconia-titanium composites
Paula Łada 0 1 2
Aleksandra Miazga 0 1 2
Katarzyna Konopka 0 1 2
Mikołaj Szafran 0 1 2
0 Faculty of Chemistry, Warsaw University of Technology , 3 Noakowskiego St., 00-664 Warsaw , Poland
1 Faculty of Materials Science and Engineering, Warsaw University of Technology , 141 Woloska St., 02-507 Warsaw , Poland
2 & Paula Łada
The dilatometric and thermogravimetric methods were used to investigate the sintering conditions of 3Y-ZrO2 and 3Y-ZrO2-Ti composites. For the materials preparation, the nanometric zirconia stabilized by 3 mol% Y2O3 powder and micrometric titanium powder (3 and 10 vol%) were used. The green body samples were formed by slip casting method. The morphology of samples microstructures was determined by SEM observations. The stereological analysis of zirconia and zirconia-titanium composites was carried out using computer program. The density was measured using the Archimedes method. The hardness of sinters was also investigated. Addition of Ti into ZrO2 influenced the sintering behavior and thermal expansion of obtained composites. The analysis of the sintering process and characteristic temperatures confirmed the increase of onset and final temperature of shrinkage with the increase in Ti content. The changes of the thermal expansion curves for the pure zirconia and 3Y-ZrO2-Ti composites were the result of the aTi ? bTi transformation and the transition temperature of the zirconia m ? t transformation. The zirconia and composite samples were characterized by relative density about 98%, close to theoretical density. The slight growth of zirconia grains was observed.
Zirconia; Titanium; Dilatometry; Thermal expansion; Composites; Stereology
Due to the properties, such as high strength, chemical
stability, high thermal shock resistance, advanced
biocompatibility, and high fracture toughness, yttria-stabilized
zirconia is very popular ceramic material with the wide
range of application in science and technology [
are used as oxygen sensors, thermal barrier coatings, or
medical implants and prosthesis [
Production of the composites with zirconia matrix is the
response to the research for new materials with better,
innovative properties. One of the solutions is the addition
of metal particles into zirconia [
]. Titanium is
characterized by high chemical resistance, biocompatibility, high
fatigue resistance, low thermal and electrical conductivity,
no magnetic properties, and also high melting point
(1667 C) [
]. Due to these properties, it is a good
component for the zirconia-based composites, especially
for the biomedical applications. Additionally, the addition
of Ti to zirconia ceramic materials decreases hardness and
stiffness of composite material but it also increases fixation
of the implant in the bone [
Determination of sintering temperature for the 3Y–
ZrO2–Ti composites is one of the important steps to obtain
the material characterized by high relative density.
Furthermore, reaction between components may vary
depending on the temperature. The study of reaction
between zirconia and titanium was subject of the many
researches. The first studies of the ZrO2–Ti system were
carried out for the stabilization of zirconia by various kinds
of dopants and the reaction of liquid titanium and its alloys
due to the problem with ceramic molds for casting [
The observations of the reaction between titanium and
ZrO2 led to further studies at temperatures below the
melting point of titanium [
]. In results, Lin et al. [
indicated the influence of the heating temperature of the
reaction at the interface between zirconia and titanium. The
temperature influences on the microstructure, composites
phase composition, and the grain growth of zirconia.
Moreover, the new phases from Zr–Ti–O system were
Pure zirconia ceramics exhibit a phase transformation
between monoclinic (m-ZrO2) to tetragonal (t-ZrO2)
phases. The temperature of the m ? t transformation during
the heating is close to 1400 C. The zirconia stabilization
by the 3 mol% Y2O3 eliminated the reverse t ? m
transformation during the cooling. However, the titanium
addition could affect the changes of m ? t transformation
temperatures and the amount of monoclinic phase in the
sintered material [
3, 19, 20
In the literature, data are many papers about the thermal
behavior of yttria-stabilized zirconia ceramic [
zirconia composites with Ti particle are still the new
materials, which require the investigation of the thermal
behavior during the sintering process. The aim of this work
was the preparation of 3Y–ZrO2–Ti composites with
different content of titanium particles. The forming method
was slip casting. The thermal expansion and physical
properties were the subject of the investigation. The result
will allow designing composites of 3Y–ZrO2–Ti system.
Conducting this type of research will allow to consciously
designing materials from 3Y–ZrO2–Ti system.
Materials and experimental procedure
The starting materials were commercial zirconia powder
stabilized by 3 mol% Y2O3 (Tosoh, Japan) and pure
titanium powder (Alfa Aesar, USA). Powders were
characterized by the density of 5.92 and 4.45 g cm-3,
respectively. The densities of powders were determined by
a helium pycnometer AccuPyc 1340 II. The average
particle diameters were measured by using SEM and were
lower than 100 nm (3Y–ZrO2) and about 8–11 lm (Ti),
The green bodies were formed by the slip casting
method. The slip casting slurry was consisted of zirconia
and titanium powders with the distillate water as a solvent
(55 vol%) and diammonium hydrocitrate as a deflocculant
(0.3 mass%—with respect to the mass of solid phase). The
preparation of the slip casting slurries based on own earlier
research. The detailed description of the procedure and
characterization of slip casting slurries were presented in
the paper [
]. Titanium powder content in the composite
samples was 3 and 10 vol%, respectively. Moreover, for
comparative purposes, the pure zirconia samples were
The thermal analysis has been done for 3Y–ZrO2–Ti
green body samples. Differential thermal analysis (DTA)
and thermogravimetric (TG) curves were obtained by using
Netzsch STA 449C coupled with Quadrupole Mass
Spectrometer Netzsch QMS 403C. The final temperature was
1450 C, and the heating rate was 10 C min-1 in the
constant flow of two gases: argon 10 mL min-1 (protective
gas) and argon 60 mL min-1 (measurement gas). Mass
spectrometer was set to detect m/z values in mass range
The cylindrical green bodies (h = 10 mm, d = 8 mm)
prepared by slip casting method were tested in a
differential dilatometer (Netzsch Dil 402E with the graphite
furnace). The characteristic sintering temperatures were
observed during the heating with heating rate of
10 C min-1 in helium atmosphere. The temperature
measurement range was 40–1450 C.
Selected physical properties were measured by
Archimedes method. The hardness of the samples was
determined by using Vickers hardness tester HVS-30T, Huatec
The morphology of samples cross section was studied
by SEM Hitachi SU-70. For observation, the samples were
coated with a thin layer of carbon. The grain growth
measurement was conducted for samples after thermal
etching at 1350 C (100 C lower than sintering
temperature), during the 30 min. Thermal etching allowed to
determine zirconia grain size. The samples were also
coated with a thin layer of carbon for observation after
thermal etching. The first step was SEM observations of the
zirconia matrix microstructure. The next step was
stereological analysis on the image from SEM, which was
conducted by using computer program MicroMeter [
zirconia grains were described by the equivalent diameter
(d2) (diameter of a circle having the same area as the
surface of grain).
The sintered cylindrical samples were tested to obtain
the thermal expansion curves from test with heating rate of
10 C min-1. The temperature measurement range was
40–1450 C by using a differential dilatometer in helium
All research was conducted with the using of inert gas
atmosphere (helium and argon). For the preparation of
zirconia–titanium composite, very necessary is the kind of
sintering atmosphere. Titanium is characterized by high
affinity for oxygen, nitrogen, and hydrogen. For the limited
the reaction of these elements with Ti particle during the
sintering process, the inert atmosphere should be used.
Results and discussion
Reaction sintering process
Figure 1 shows the temperature plots characterized by
variation in mass (TG curve) and thermal flow (DTA
curve) during heating of selected samples—3Y–ZrO2–
10 vol% Ti. The samples were prepared by slip casting
method with the addition of deflocculant in the water
solution. Heating of the powder up to 1450 C is followed
by increase in its mass by 0.45%. The small mass loss was
observed for temperature range of 400–600 C, which
corresponded with the degradation of the slip casting
additives. The results of mass spectrum measurement
showed the existence of the peaks with m/z = 18, 28, and
44 in the mass spectrum taken within this temperature
range, which were attributed to the molecules H2O, CO,
and CO2, respectively, released from the powder sample.
Removal of the slip casting additives did not result in peaks
on the DTA curves. The DTA curve showed one
exothermic effect at 838.6 C. These thermal changes were
associated with a titanium oxidation and aTi ? bTi phase
transformation. The aTi ? bTi transformation
temperature for Ti is 882.5 C [
Figure 2 shows the variation in the shrinkage rate of
zirconia and 3Y–ZrO2–Ti samples as a function of heating
temperature. The characteristic temperatures of the
samples sintering are included in Table 1. The maximum
densification rate for the samples under study falls at the
m ? t transformation temperature about 1300 C and
increases together with the increase of Ti content. The most
valuable information is the onset temperature of
macroscopic shrinkage. That is, the minimum temperature
corresponding to starting of sudden decrease in the sample
length due to the beginning of bulk sintering. The onset
temperature of sintering increases with an increase of
titanium content. The titanium content also had the
influence on the shrinkage value of the samples. The lowest
values of the shrinkage were observed for the pure zirconia
sample. The addition of titanium gives the increase of the
shrinkage. Figure 2 presented also the plot for dL/dt versus
temperature which corresponds with the microscopic
sintering, where the shrinkage taking place within an
agglomerate of powders.
Table 2 shows the selected physical properties of zirconia
and zirconia–titanium composites. Although the green
densities of sample series were significantly differed, the
relative density of the sinters was similar and close to
theoretical densities for pure zirconia ceramic and 3Y–
ZrO2–Ti composites. The addition of titanium did not
influence on density of final material. Furthermore, the 3Y–
ZrO2–3 vol% Ti composite was characterized by similar
hardness to pure zirconia, but the addition of 10 vol% Ti
slightly decreased the composite hardness. The open
porosity was low and similar for all samples.
The cross sections of samples were presented in Fig. 3
(a–c—for pure zirconia and zirconia–titanium composites,
respectively). Slip casting method allowed forming
composites with the homogeneous distribution of Ti-rich
particles. The microstructures of pure zirconia and zirconia
matrix of the composite samples after thermal etching were
presented in Fig. 3a1, b1, c1.
The addition of titanium did not affect the zirconia
particles’ size distribution in the samples (Fig. 4). The
mean grain size slightly increased with the increase of Ti
content (Table 3). This can be related to the process of
forming a new phase between Ti–ZrO2 and therefore
formation of zirconia with reduced oxygen content. Such
99.0 m/z 18
changes of new phases from Ti–Zr–O system were
observed in the literature earlier [
The thermal expansion and shrinkage curves of the
studied materials are plotted in Fig. 5. The linear
dimension for all samples, pure zirconia and 3Y–ZrO2–Ti
composites, was increased during the heating. However, the
character of changes was different. The shrinkage for pure
zirconia was linear up to 1300 C. For the composite
samples the curves of shrinkage were diffrent. The 3Y–
ZrO2 - 3 vol.% Ti composite sample was characterized by
shrinkage close to linear curve at temperatures range of
50–1200 C and significant increase above 1200 C. The
shrinkage curve of 3Y–ZrO2 - 10 vol.% Ti increased in
non linear way.
Pure zirconia and 3Y–ZrO2–3 vol% Ti samples were
characterized by similar thermal expansion curve at
temperature range of 50–1200 C with a * 11 9 10-6 K-1.
The small difference was observed for the temperature of
550 C (a * 8.2 9 10-6 K-1) which could correlate with
the beginning of the titanium oxide changes [
about 1300 C, the pure zirconia thermal expansion
coefficient was decreased, which is related to the m ? t
transformation and the linear dimension changes (curve I)
]. Course of the second (II) curve was different at
thermal heating: 3Y–ZrO2 (a1) and 3Y–ZrO2 matrix in the
composites (b1 and c1, respectively), SEM
temperatures higher than 1300 C. The thermal expansion
coefficient slightly increased. At the same temperature, the
thermal expansion coefficient of the composite with
3 vol% Ti was increased which was associated with the
small addition of Ti and the transition temperature
conversion of m ? t transformation (curve I) [
slightly lower increase was observed for the second
In the samples with upper Ti additive (10 vol%) in the
composite samples, the significant differences were
observed. At the temperature range of 50–1200 C, the
thermal expansion curve (I) was closed to linear with two
characteristic points at 650 C and 1000 C. At 650 C, the
small decrease in the thermal expansion coefficient was
observed (about - 2.5 9 10-6 K-1). This range of
temperature could correspond with the titanium oxides
]. At the second temperature point (below
1000 C), the thermal expansion coefficient was higher,
about 10 9 10-6 K-1. This point could associate with high
addition of Ti (10 vol%) which reveal in the aTi ? bTi
transformation . Likewise, the curve at the temperature
above 1200 C had different characteristics. At the
temperature range of 1200 C and 1400 C, the rapid growth
of thermal expansion was detected because of the m ? t
zirconia transformation. In the range of temperature
1300–1450 C, the same rapid decrease of thermal
expansion was observed in all samples. The second thermal
expansion curve (II) was more stable in the whole range of
temperature without one characteristic point about 400 C
which was corresponded with the beginning of the titanium
Addition of Ti into ZrO2 strongly influenced the sintering
behavior and thermal expansion of composites.
The thermal expansion curves were different for the
pure zirconia and 3Y–ZrO2–Ti composites. The changes
were the result of the existing aTi ? bTi transformation
and the transition temperature conversion of zirconia
m ? t transformation.
The data obtained from the mass spectrometer coupled
with the thermobalance reveal that the predominant
gaseous products released from the samples during thermal
treatment are H2O, CO2, and CO in the case of the
measurements carried out in Ar atmosphere. At 838.6 C,
probably the exothermic reaction of aTi ? bTi was
Selected temperature of fabrication of ZrO2–Ti
composites was 1450 C. The analysis of the sintering process
and characteristic temperatures confirmed the influence of
the Ti addition on the onset and final temperature of
shrinkage which increased with the increase of Ti content.
The maximum shrinkage temperatures were about
Using the slip casting method allowed producing the
zirconia and composite samples with the relative density
about 98%, close to theoretical density. The addition of
titanium did not significantly decrease the material
hardness. The microstructure observations showed the
homogeneous distribution of the Ti-rich phase areas in the
composite samples. The zirconia grain size slightly
increased with the increase of Ti content.
Determining sintering conditions and its effect on the
properties of zirconia–titanium composites are the basis for
further analyses. The next step of investigation should be
the phase analysis of composites and description the
microstructure on the particle–matrix interface.
Acknowledgements The work was done in frame of the project
financed by National Science Centre (NCN), Project DEC-2013/11/B/
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1. Bowen P , Carry C . From powder to sintered pieces: formation, transformation and sintering of nanostructured ceramic oxides . Powder Technol . 2002 ; 128 : 248 - 55 .
2. Miller RA. Current status of thermal barrier coatings: an overview . Surf Coat Technol . 1987 ; 30 : 1 - 11 .
3. Chevalier J , Gremillard L , Virkar AV , Clarke DL . The tetragonal-monoclinic transformation in zirconia: lesson learned and future trends . J Am Ceram Soc . 2009 ; 92 ( 9 ): 1901 - 20 .
4. Zender H , Leistner H , Searle H. ZrO2 materials for applications in the ceramic industry . Int Ceram . 1990 ; 39 ( 6 ): 33 - 6 .
5. Vogt T , Hunter BA , Thornton J . Structural evolution of thermalsprayed yttria-stabilized ZrO2 thermal barrier coatings with annealing: a neutron diffraction study . J Am Ceram Soc . 2001 ; 84 ( 3 ): 678 - 80 .
6. Kosmac T , Oblak C , Marion L. The effects of dental grinding and sandblasting on ageing and fatigue behaviour of dental zirconia (Y-TZP) ceramic . J Eur Ceram Sci . 2008 ; 28 : 1085 - 90 .
7. Wildan M , Edrees HJ , Alan H . Ceramic matrix composites of zirconia reinforces with metal particles . Mater Chem Phys . 2002 ; 75 ( 1-3 ): 276 - 83 .
8. Bartolome JF , Gutierrez-Gonzalez CF , Pecharroman C , Moya JS . Synergistic toughening mechanism in 3Y-TZP/Nb composites . Acta Mater . 2007 ; 55 : 5924 - 33 .
9. Niinomi M. Mechanical properties of biomedical titanium alloys . Mater Sci Eng . 1998 ;A243: 231 - 6 .
10. Boyer R , Collings EW , Welsch G . Materials properties handbook: titanium alloys . ASM Int . 1994 ; 1 - 55 .
11. Mehrali M , Shirazi FS , Mehrali M , Metselaar HSC , Kadri NAB , Osman NAA . Dental implants from functionally graded materials . J Biomed Mater Res A . 2013 ; 101 ( 10 ): 3046 - 57 .
12. Gain AK , Zhang L , Quadir MZ . Composites matching the properties of human cortical bones: the design of porous titanium zirconia (Ti-ZrO2) nanocomposites using polymethyl methacrylate powders . Mater Sci Eng A . 2016 ; 662 : 258 - 67 .
13. Kaliaraj GS , Kirubaharan K , Pradhaban G , Kuppusami P , Vishwakarma V . Isolation and characterization of biogenic calcium carbonate/phosphate from oral bacteria and their adhesion studies on YSZ-coated titanium substrate for dental implant application . Bull Mater Sci . 2016 ; 39 ( 2 ): 385 - 9 .
14. Weber BC , Garrett HJ , Mauer FA , Schwartz MA . Observation on the stabilization of zirconia . J Am Ceram Soc . 1956 ; 39 ( 6 ): 197 - 206 .
15. Ruh R , Tallan NM , Lipsitt HA . Effect of metal additions on the microstructure of zirconia . J Am Ceram Soc . 1964 ; 47 ( 12 ): 632 - 5 .
16. Lin KL , Lin CC . Zirconia-related phases in the zirconia/titanium diffusion couple after annealing at 1100-1550 C. J Am Ceram Soc . 2005 ; 88 ( 10 ): 2928 - 34 .
17. Lin KL , Lin CC . Effects of annealing temperature on microstructural development at interface between zirconia and titanium . J Am Ceram Soc . 2007 ; 90 ( 3 ): 893 - 9 .
18. Lin KL , Lin CC . Ti2ZrO phases formed in the titanium and zirconia interface after reaction at 1550 C . J Am Ceram Soc . 2005 ; 88 ( 5 ): 1268 - 72 .
19. Matsui K , Yoshida H , Ikuhara Y . Grain-boundary structure and microstructure development mechanism in 2-8 mol% yttria-stabilized zirconia polycrystals . Acta Mater . 2008 ; 56 : 1315 - 25 .
20. Munoz-Tabares JA , Jimenez-Pique E , Reyes-Gasga J , Anglada M. Microstructural changes in ground 3Y-TZP and their effect on mechanical properties . Acta Mater . 2011 ; 59 : 6670 - 83 .
21. Ding LX , Wang L , Nagashima M , Hayakawa M. A dilatometric study of the martensitic transformation of zirconia containing 1.8-2.0 mol% yttria . Mater Trans . 2001 ; 42 ( 3 ): 450 - 2 .
22. Surzhikov AP , Ghyngazov SA , Frangulyan TS , Vasil'ev IP , Chernyavskii AV . Investigation of sintering behaviour of ZrO2 (Y) ceramic green body by means of non-isothermal dilatometry and thermokinetic analysis . J Therm Anal Calorim . 2017 ; 128 ( 2 ): 787 - 94 .
23. Lopez-Lopez E , Baudin C , Moreno R . Thermal expansion of zirconia-zirconium titanate materials obtained by slip casting of mixtures of Y-TZP-TiO2 . J Eur Ceram Soc . 2009 ; 29 : 3219 - 25 .
24. Lada P , Falkowski P , Miazga A , Konopka K , Szafran M. Fabrication of ZrO2-Ti composites by slip casting method . Arch Metall Mater . 2016 ; 61 ( 2B ): 1095 - 100 .
25. Wejrzanowski T , Pielaszek R , Opalinska A , Matysiak H , Łojkowski W , Kurzydłowski KJ . Quantitative methods for nanopowders characterization . Appl Surf Sci . 2006 ; 253 : 204 - 8 .
26. Wahlbeck PC , Gilles PW . Reinvestigation of the phase diagram for the system titanium-oxygen . J Am Ceram Soc . 1966 ; 49 ( 4 ): 180 - 3 .
27. Teng LD , Wang FM , Li WC . Thermodynamics and microstructure of Ti-ZrO2 metal-ceramic functionally graded materials . Mater Sci Eng . 2000 ;A293: 130 - 6 .
28. Basu B , Vleugels J , Van Der Biest O . Transformation behaviour of tetragonal zirconia: role of dopant content and distribution . Mater Sci Eng A . 2004 ; 366 ( 2 ): 338 - 47 .
29. Domagala RF , Lyon SR , Ruh R. The pseudobinary Ti-ZrO2 . J Am Ceram Soc . 1973 ; 56 ( 11 ): 584 - 7 .
30. Teng LD , Li WC , Wang FM . Effect of Ti content on the martensitic transformation in zirconia for Ti-ZrO2 composites . J Allloys Compd . 2001 ; 319 : 228 - 32 .