A Novel and Simple Route to Synthesis Nanocrystalline Titanium Carbide Via the Reaction of Titanium Dioxide and Different Carbon Source

doi:10.4236/msa.2011.211215

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Materials Science s a nd Applications, 2011, 2, 1622-1626

doi:10.4236/msa.2011.211215 Published Online November 2011 (http://www.SciRP.org/journal/msa)

A Novel and Simple Route to Synthesis

Nanocrystalline Titanium Carbide via the

Reaction of Titanium Dioxide and Different

Carbon Source

Youjian Chen1, Yongyong Deng1, Hong Zhang1, Lihua Wang3, Jianhua Ma1,2*

1College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou, China; 2Nanomaterials and Chemistry Key Labo-

ratory, Advanced Materials Research Center of Wenzhou, Wenzhou University, Wenzhou, China; 3Shimadzu International Trading

(Shanghai) Co., Ltd., Guangzhou, China.

Email: *[email protected]

Received September 10th, 2011; revised October 25th, 2011; accepted November 6th, 2011.

ABSTRACT

A novel and simple route for synthesizing nanocrystalline ceramic powders in molten salt was introduced in the paper.

Titanium carbide (TiC) was prepared via the reaction of metallic magnesium powders with titanium dioxide (TiO2),

carbon source and molten salt in an autoclave at 650˚C. Carbon source (oxalic acid and citric acid) in this paper was

stable, low toxic and cheap. X-ray powder diffraction (XRD) patterns indicated that the products were cubic TiC.

Scanning electron microscopy (SEM) images showed that the samples consisted of particles with an average size of 200

nm and 100 nm in diameter, respectively. Energy Dispersive Spectrometer (EDS) analysis of the samples suggested the

products contained carbon and titanium elements. The product was also studied by the thermogravimetric analysis

(TGA). It had good thermal stability and oxidation resistance below 350˚C in air.

Keywords: Titanium Carbide, Chemical Synthesis, X-Ray Diffraction, Scanning Electron Microscopy

1. Introduction

It is known that transition metal carbides have found

extensive applications in many fields, such as cutting tools,

wear-resistant parts and high-temperature structural ma-

terials because of their outing properties, such as high

hardness, high melting point, high thermal conductivity,

high strength even at high temperatures, high wear and

corrosion resistance, and a high degree of chemical sta-

bility [1-3]. Recently, much attention has been paid to

their catalytic properties because they exhibit activities

similar to those of the noble metals [4].

Titanium carbide (TiC) is one of the most important

compounds among transition metal carbides, due to its

promising physical and chemical properties, such as a

high melting temperature (3140˚C), a high boiling tem-

perature (4820˚C), high Vickers hardness (28 - 35 GPa),

high Young’s modulus (410 - 450 GPa), low density

(4.93 g·cm–3), high flexure strength (240 - 400 N/mm2),

good thermal conductivity (21 W/m2 × K), high resistance

to corrosion and oxidation, high abrasion resistance, and

high thermal shock resistance [5-8]. So it is widely used

for cutting materials, abrasive, anti-wear and aerospace

materials [9-11]. At the same time, it can also be used as

a substitute for tungsten carbide in cermets because they

have similar properties of high hardness and wear resis-

tance, what’s more, nickel is used as binder for TiC is

cheaper and less toxic than cobalt which WC requires as

a binder [12]. Because of the promising properties and

extensive application of TiC, it is meaningful to synthe-

size nanocrystalline TiC in a simple route at low tempe-

rature and with convenient manipulations.

Traditionally, TiC powders are commercially synthe-

sized via the reaction of titanium dioxide and carbon in

the temperature range of 1700˚C - 2300˚C for 10 - 24 h

[13], it is important to develop new technics to replace

the old method which wastes time and energy. Recently,

some new methods have been used to synthesize titanium

carbide. Chandra et al. [14] synthesized nano-TiC pow-

der using titanium gel precursor and carbon particles in

the range of 1300˚C - 1580˚C for 2 h under argon cover.

A Novel and Simple Route to Synthesis Nanocrystalline Titanium Carbide via the Reaction 1623

of Titanium Dioxide and Different Carbon Source

Qi et al. [15] reported that nanowires TiC was also

successfully synthesized by the reaction of TiO gas with

methane in the presence of a catalyst containing Fe. Tong

et al. [16] reported the thermal plasma method to synthe-

size nano-powders TiC with the average size of the TiC

powders is less than 100 nm. Lee et al. [17] reported

nano-structured TiC was synthesized by liquid-magne-

sium reduction of vaporized TiCl4 + CCl4 solution. David

et al. [18] reported high surface area, porous titanium

carbide (TiC) films have been synthesized employing

physical vapor deposition of titanium at glancing angles

under high vacuum within an ethylene ambient. Patel et

al. [19] reported Silicon-based nanocomposites containing

TiC were synthesized by high-energy mechanical milling

(HEMM).

In this paper, we have developed a new convenient

route to synthesize nanocrystalline TiC in the autoclave

by the reaction of metallic magnesium powders with

TiO2 and carbon source (oxalic acid (C2H2O4) and citric

acid (C6H8O7), separately.) in an autoclave at 650˚C. In

this route, TiO2 is more stable and safe in operation than

other titanium source (e.g. TiCl4) and metallic magne-

sium powders as reductant are also more safe and conve-

nient than other reductants (e.g. metallic sodium). Due to

the whole synthesis route that is carried out in the sealed

autoclave, so it can be obtained that all manipulations are

rather safe and convenient.

2. Experimental

TiC was synthesized by a novel method. All chemicals

were analytical grade and used without further purifi-

cation. Initially, TiO2, metallic magnesium powders (ex-

cessive) and carbon source (oxalic acid (C2H2O4) and

citric acid (C6H8O7), separately), NaCl and MgCl2 were

put into a mortar orderly with continuous stirring. Then

the mixture was transferred to a stainless steel autoclave

that was heated at 650˚C under argon atmosphere and

then cooling to room temperature naturally. The product

was collected and washed with dilute HCl, distilled water,

and absolute ethanol several times to remove all impurity

species and then dried in vacuum at 60˚C for 8 h. Black

powders were obtained.

The obtained samples were analyzed by powder X-ray

diffraction (XRD) on a Bruker D8 Advance X-ray pow-

der diffractometer using Cu K-α radiation (wave-length λ

= 1.54178 Å). 2 theta angles were from 30˚ to 90˚. The

morphologies and EDS analysis of the samples were ob-

served from a JEOL JSM-6700F scanning electron mi-

croscope.

3. Results and Discussion

Figure 1 shows the XRD patterns of the as-prepared

30 40 50 6070 80 90

2Theta/Degress

(a)

(b)

(c)

(d)

(e)

(a): 60 0oC ,10 h (b): 6 50oC ,4h

(c): 6 50oC, 6h (d): 650oC ,8h

(e): TiC,JCPDS Card no .65-8417

111 200 220 311 322

Intensity/A.U

Figure 1. XRD patterns of the as-prepared samples (oxalic

acid as carbon source) and standard pattern.

samples using oxalic acid as carbon source and TiC (JCPDS

Card no. 65-8417). Pattern (a) shows the sample pre-

pared under the condition of 600˚C and 10 h. Obviously,

the sample is not purity with other matters. Pattern (b),

Pattern (c) and Pattern (d) show that the samples are pre-

pared under the condition of 650˚C and 4 h, 6 h and 8 h,

respectively. There are five obvious diffraction peaks in

these patterns. And all these diffraction peaks ((1 1 1), (2

0 0), (2 2 0), (3 1 1), (3 2 2)) at different d-space can be

indexed as cubic titanium carbide (TiC). The refinement

gives the cell constants (a = b = c = 4.326 Å), which is

consistent with the value reported in the literature (a = b

= c = 4.325 Å) (JCPDS card no. 65-8417). No evidences

of impurities such as titanium, titanium dioxide, other ti-

tanium carbides, can be found in these XRD patterns.

Figure 2 shows the XRD patterns of the as-prepared

samples using citric acid as carbon source and TiC

(JCPDS Card no. 65-8808). Pattern (a) shows the sample

was prepared under the condition of 650˚C and 4 h, there

are five obvious diffraction peaks in this pattern. And all

these diffraction peaks ((1 1 1), (2 0 0), (2 2 0), (3 1 1),

(3 2 2)) at different d-space can be indexed as cubic

titanium carbide (TiC). The refinement gives the cell

constants (a = b = c = 4.3213 Å), which is consistent

with the value reported in the literature (a = b = c = 4.316

Å) (JCPDS card no. 65-8808). No evidences of impu-

rities such as titanium, titanium dioxide, other titanium

carbides, can be found in this XRD pattern.

The morphologies of the prepared TiC samples were

investigated by field emission scanning electron micro-

scopy. Figure 3(a), (b), (c) showed the SEM images of

the as-prepared samples using oxalic acid, which were

prepared under the reaction conditions of 650˚C and 4 h,

A Novel and Simple Route to Synthesis Nanocrystalline Titanium Carbide via the Reaction

1624

of Titanium Dioxide and Different Carbon Source

30 40 5060 70 80 90

2Theta/Degree

(b)

(a)

111 200

220

311

322

Intensity/a.u

(a) 650 oC 4h

(b) TiC JCP DS Card no. 65-880 8

Figure 2. XRD patterns of the as-prepared samples (citric

acid as carbon sour ce) and standar d pattern.

Figure 3. SEM images of the as-prepare d samples prepare d

under different reaction conditions ((a), (b) and (c) samples

using oxalic acid, (d) sample using citric acid): (a) 650˚C, 4

h; (b) 650˚C, 6 h; (c) 650˚C, 8 h; (d) 650˚C, 4 h.

6 h, 8 h, respectively. The samples showed that they con-

sisted of particles with an average diameter of 200nm. It

seemed not to affect the particle size of the samples sig-

nificantly, through varying the reaction time at the tem-

perature of 650˚C. Figure 3(d) showed the SEM image

of the as-prepared sample using citric acid, which was

prepared under the reaction conditions of 650˚C and 4 h.

The sample showed that it consisted of particles with an

average diameter of 100 nm. The reaction temperature of

the TiC samples prepared using oxalic acid and citric

acid as carbon source is 650˚C. They maybe have poten-

tial for the economy and efficiency of synthesis of TiC

nanopowders for industrial applications. Compared to ci-

tric acid as carbon source, the size of the particles pre-

pared using oxalic acid as carbon source shows increase.

These particles exhibit slightly agglomerated particle mor-

phology due to the ultrafine size of the sample.

The EDS figures of the prepared TiC samples were

shown in the Figure 4 and Figure 5. The EDS images of

the as-prepared TiC samples were prepared under differ-

rent reaction conditions. Figure 4 showed the sample

was prepared under the condition of 650˚C and 4 h using

oxalic acid as carbon source, and Figure 5 showed the

sample was prepared under the condition of 650˚C and 4

h using citric acid as carbon source. According to the

EDS results, the products are composed of C, Ti, Zn, Cu

elements, without the contamination of oxygen. Both Zn

and Cu come from the copper plateform. It can be con-

cluded that the selectional particulates may be TiC. It can

be found that TiC particulates in a great measure are 200

nm and 100 nm, respectively. Furthermore, the weight

percentage of Titanium and carbon analyzed by EDS

Figure 4. EDS of the sample prepared under the condition

of 650˚C and 4 h using ox alic acid as carbo n sour ce.

Figure 5. EDS of the sample prepared under the condition

of 650˚C and 4 h using citric acid as car bon source.

A Novel and Simple Route to Synthesis Nanocrystalline Titanium Carbide via the Reaction 1625

of Titanium Dioxide and Different Carbon Source

were 55.63:17.90 in the Figure 4 and 60.73:23.29 in the

Figure 5; while the atomic ratio of Titanium and carbon

were 0.77:1.00 and 0.66:1.00, separately.

We are in order to investigate the thermal stability and

the oxidation resistance of the as-prepared TiC powders

using oxalic acid that they were prepared under the con-

dition of 650˚C and 8 h by the thermogravimetric ana-

lysis (TGA), which was carried out at temperatures be-

low 1000˚C under flowing air and nitrogen gases. We

can find that the weight of the product has changed slight-

ly below 400˚C. A weight loss indicates that the sample

might adsorb a little water on the surface. In this stage,

the sample is very stable. After about 400˚C, TiC sample

is found to begin slowly oxidized, which indicates that

the sample is oxidized by oxygen to form titanium oxide

and carbon dioxide, titanium oxides, both stoichiometric

and nonstoichiometric (TiO2, Ti3O5, Ti2O3, TiO) may be

formed during the oxidation process. We can conclude

from the curve of Figure 6 that more quantity of titanium

oxide should be increased along with further oxidation.

As the temperature rises from 400˚C to 850˚C, there is an

obvious weight gain during the process, indicating that

the TiC sample is oxidized into titanium oxide and car-

bon dioxides. Between 850˚C and 920˚C, the carbon dio-

xide generated in the simple surface slowly released may

induce a small weight loss. Above 920˚C, the weight gain

remains almost constant. We also can find that the weight

of the product has changed slightly below 1000˚C under

flowing nitrogen gases, this is because that the sample

might adsorb nitrogen gases on the surface.

It was suggested that reaction temperature had a sig-

nificant influence on the formation of TiC. The XRD pa-

tterns of the as-prepared samples were synthesized under

different temperature, time conditions and different car-

0100 200 300 400 500 600700 800 90010001100

-5

Weight gain /%

Temperature (oC)

(a)

(b)

(a) :flowing air

(b) :flowing nitrogen gases

Figure 6. TGA curves in flowing air and nitrogen gases of

the as-prepared TiC sample using oxalic acid prepared un-

der the condition of 650˚C and 8 h.

bon source. The SEM images of these samples are shown

in Figure 3. From the XRD patterns, we can easily obtain

conclusion that TiC could be synthesised when the re-

action temperature is 600˚C, but the crystallinity is not

very good, and has some impurities such as Ti can be

found in the Figure 1(a). When the temperature is 650˚C,

the crystallinity of the sample is very good, and no evi-

dences of crystal impurities such as titanium, titanium

oxides, other titanium carbides, can be found in these

XRD patterns. An optimum temperature for the forma-

tion of nanocrystalline TiC is about 650˚C. Varying the

reaction time at 650˚C did not significantly affect the

particle size of the as-prepared TiC shown in Figure 3(a)-

(c). However, the carbon source in the reaction processes

can affect the size of the products. Compared to citric

acid as carbon source, the size of the particles prepared

using oxalic acid as carbon source shows increase.

In our experiments, as the temperature rising, C2H2O4

and C6H8O7 could decompose generating carbon oxides

gases. So the pressure in the autoclave may be very high.

The high pressure in the autoclave would be helpful for

reducing the reaction temperature and enhancing the re-

action speed. At the reaction temperature, TiO2, carbon

oxides gases and metallic magnesium powders could re-

act with each other to produce cubic TiC. The total re-

action process can be represented as the following:

2TiO2 + 10Mg + C2H2O4·2H2O → 2TiC + 10MgO + 3H2

C6H8O7 + 19Mg + 6TiO2 → 6TiC + 19MgO + 4H2

4. Conclusions

In summary, nanocrystalline cubic TiC has been pre-

pared via a simple thermal route by the reaction of me-

tallic magnesium powders with titanium dioxide (TiO2)

and carbon source (oxalic acid and citric acid) in molten

salt at 650˚C for 4 h. The product crystalline structure is

cubic. It consists of particles with an average size of 200

nm and 100 nm, respectively. Compared to other carbon

source (e.g. CCl4), carbon source in this paper is stable,

low toxic and cheap, it can be obtained that all manipu-

lations are rather safe and convenient. This simple che-

mical synthesis route maybe provide a new method to

prepare other transition metal carbides.

5. Acknowledgements

This work was supported by Innovation and Promotion

of science-technology project of Zhejiang Province and

Department of Education of Zhejiang Province of China

under Grant No. 20070546.

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