**2. Experimental data**

#### **2.1. Initial hypothesis**

To obtain titanium carbides, a chemical analysis was conducted:

$$\text{TiO}\_2 + \text{C} + \text{Al} \rightarrow \text{TiC} + \text{Al}\_2\text{O}\_3 \tag{1}$$

On performing the balancing of Eq. (1), we have.

<100 nm, can be produced. These metastable phases characteristically have an interesting combination of physical, chemical, mechanical, and magnetic properties that are now being

Mechanically alloyed materials are used in a variety of industries. They are used in the synthesis and processing of advanced materials (magnetic, superconducting, and ceramic materials) such as intermetallic materials, nanocomposites, catalysts, hydrogen-storage materials, gas heaters and dampers, and modifiers of the solubility of organic compounds for waste management and fertilizer production [4]. However, the main industrial applications of mechanically alloyed materials have been in heat treatments, glass processing, energy production, and the aerospace industry. When in the search for materials which meet increasingly strict requirements, such as high rigidity, high mechanical strength, and low density, such processes as powder technologies and mechanical alloying emerge. These processes do not have any limitations unlike conventional processes, for example, the melting process [5], which is not viable when there are materials with very different melting temperatures, low solubility limits, manufacturing costs due to high energy consumption, and environmental impact problems. In this respect, the mechanical alloying is a non-traditional technique, industrially competitive in obtaining composite materials, easy to use, low cost, and environmentally friendly [6]. This process produces alloys in solid state from elemental powders of any type of material [1], using the impact energy produced by milling elements. The materials produced by mechanical alloying have a good thermal stability of their mechanical properties. The stability of the mechanical strength is due to the uniform dispersion (with a spacing range of 100 nm) with very fine oxide particles (5–50 nm), which are stable at high temperatures, and inhibit the movement of dislocations in the metallic matrix and increase the strength of the creep deformation alloy. Other characteristic is a fairly homogeneous distribution of the elements of the alloy during the mechanical alloying that gives rise to a solid solution (strengthening) and precipitation-hardening alloys with more stability at high tem-

explored due to their potential applications [3].

116 Powder Technology

peratures and a general improvement of the mechanical properties.

To obtain titanium carbides, a chemical analysis was conducted:

ally needed, due to the unfavorable conditions of use.

**2. Experimental data**

**2.1. Initial hypothesis**

The materials obtained by mechanical alloying also have excellent resistance to oxidation and corrosion, which is mainly due to the homogeneous distribution of the alloying elements and adhesion between particles [7, 8]. Due to these characteristics, these materials are widely used in aerospace applications [9], where materials with high mechanical performance are gener-

In this sense, this chapter presents the process for obtaining titanium carbides (TiC) at a laboratory level. The TiC was obtained from elemental powders of titanium dioxide, aluminum, and graphite by means of the mechanical alloying technique, using a semi-industrial capacity attritor mill.

$$\text{STIO}\_2 + \text{\textdegree C} + \text{4Al} \rightarrow \text{\textdegree TiC} + \text{2Al}\_2\text{O}\_3 \tag{2}$$

From Eq. (2), the molar mass of the elements involved in the reaction was determined and the weight of the powders involved in the mechanical alloying process was calculated (**Table 1**). The percentage of participation for each initial powder was calculated as.

$$\text{°6}\text{ }\text{@Re}\text{ }\text{acttivo}=\frac{\text{W}}{\text{W}\_{\text{s}}}\text{x1}\text{00}\text{\textdegree}\text{ }\tag{3}$$

where *W* is the weight of the reactive powder and *Wt* is the total weight of the reagent. So,

$$\%TiO\_2 = \frac{239.7}{383.7} \text{x1}000\% = 62.4\% \text{o} \tag{4}$$

$$\text{°@}\% C = \frac{\text{36.0}}{\text{383.7}} \text{x100\%} \text{°@}\% = \text{9.4\%} \text{ó} \tag{5}$$

$$1\,\% Al = \frac{108.0}{383.7} \,\text{x100\%} = 28.1\,\% \tag{6}$$

#### **2.2. Milling characteristics**

During the experimental process, three initial millings were made: two wet millings and one vacuum dry milling, in order to fine-tune the process parameters. Once the process parameters have been fine-tuned (**Table 2**), milling was performed to obtain the TiC.


**Table 1.** Balancing chemical.

(1)


**Table 2.** Experimental process details of powder grinding.

#### *2.2.1. The mill*

To make the millings, an attritor-type ball mill was used; it was developed and built by Universidad Autónoma de Occidente for this purpose (www.uao.edu.co) (**Figure 1**). The bowl of the mill has a maximum capacity of 2 l and the impeller has a rotation speed of 500 rpm. The bowl has a torispherical lid and the assembly is able to withstand temperatures over 300°C and pressures of 1.72 MPa (175 psi), which ensures a protective atmosphere. The mill also has a cooling system that allows the control of the internal temperature of the milling and a vacuum system with an Alcatel Adixen vacuum pump model 2005 SD for a

were used. For more details of the design of the attritor mill, it is recommended to read

For the milling 1-wet is called this way because 4% by weight of liquid ethanol was added as the process-controlling agent (PCA). The total amount of powders used in the milling was 500

The *Mpowder/Mballs* mass ratio determines the mass of balls that impact with regard to the mass of the powder material. At laboratory level, the recommended relationships [11] are between 10/1 and 20/1. For this milling, a ratio of 20/1 was selected, in order to have a greater amount

<sup>1</sup> <sup>⇒</sup> *Mballs* <sup>=</sup> (2 <sup>×</sup> 0.5 kg) \_\_\_\_\_\_\_\_\_\_\_\_\_\_

For this milling, the agitator shaft speed was 250 rpm, the milling time was 5 h, and the pro-

For the milling 2-wet, a total of 250 g of powder was used (**Table 4**); the most critical work parameters of the equipment were selected, in order to have the maximum available energy and ensure the formation of titanium carbide. Thus, 4% (10 g) by weight was added as the

of impact energy. Therefore, the mass of the balls (*Mballs*) is calculated as

= \_\_20

**Material Percentage (%) Powders mass (g)**

**Material Percentages (%) Powders mass (g)**

Titanium dioxide 62.47 156.2 Graphite 28.13 70.3 Aluminum 9.4 23.5 Total initial powder 250.0

Titanium dioxide 62.47 312.35 Graphite 28.13 140.5 Aluminum 9.4 47.0 Total initial powder 100 500.0

**Table 3.** Amount and percentages of the initial powders of the wet grinding 1.

**Table 4.** Amount and percentages of the initial powders of the wet grinding 2.

*Mballs Mpowder*

cess was conducted at an atmospheric pressure.

/h flow. The alloy steel balls with a 10-mm-diameter

Titanium Carbide (TiC) Production by Mechanical Alloying

http://dx.doi.org/10.5772/intechopen.76690

119

<sup>1</sup> = 10 kg (7)

vacuum pressure of 1 Pa and a 5.4 m<sup>3</sup>

Botero et al. [10].

and 20 g of ethanol (**Table 3**).

\_\_\_\_\_\_

dispersing agent (PCA).

**Figure 1.** Attritor-type ball mill.

The mill also has a cooling system that allows the control of the internal temperature of the milling and a vacuum system with an Alcatel Adixen vacuum pump model 2005 SD for a vacuum pressure of 1 Pa and a 5.4 m<sup>3</sup> /h flow. The alloy steel balls with a 10-mm-diameter were used. For more details of the design of the attritor mill, it is recommended to read Botero et al. [10].

For the milling 1-wet is called this way because 4% by weight of liquid ethanol was added as the process-controlling agent (PCA). The total amount of powders used in the milling was 500 and 20 g of ethanol (**Table 3**).

The *Mpowder/Mballs* mass ratio determines the mass of balls that impact with regard to the mass of the powder material. At laboratory level, the recommended relationships [11] are between 10/1 and 20/1. For this milling, a ratio of 20/1 was selected, in order to have a greater amount of impact energy. Therefore, the mass of the balls (*Mballs*) is calculated as

$$\frac{M\_{\text{alls}}}{M\_{\text{pour}}} = \frac{20}{1} \Rightarrow M\_{\text{balls}} = \frac{(2 \times 0.5 \text{ kg})}{1} = 10 \text{ kg} \tag{7}$$

For this milling, the agitator shaft speed was 250 rpm, the milling time was 5 h, and the process was conducted at an atmospheric pressure.

For the milling 2-wet, a total of 250 g of powder was used (**Table 4**); the most critical work parameters of the equipment were selected, in order to have the maximum available energy and ensure the formation of titanium carbide. Thus, 4% (10 g) by weight was added as the dispersing agent (PCA).


**Table 3.** Amount and percentages of the initial powders of the wet grinding 1.


**Table 4.** Amount and percentages of the initial powders of the wet grinding 2.

**Figure 1.** Attritor-type ball mill.

*2.2.1. The mill*

118 Powder Technology

To make the millings, an attritor-type ball mill was used; it was developed and built by Universidad Autónoma de Occidente for this purpose (www.uao.edu.co) (**Figure 1**). The bowl of the mill has a maximum capacity of 2 l and the impeller has a rotation speed of 500 rpm. The bowl has a torispherical lid and the assembly is able to withstand temperatures over 300°C and pressures of 1.72 MPa (175 psi), which ensures a protective atmosphere. A mass ratio of 40/1 was used, for which a ball mass was obtained:

$$\frac{M\_{\text{hill}}}{M\_{\text{pural}}} = \frac{40}{1} \implies M\_{\text{hill}} = \frac{\{40 \times 0.5 \text{ kg}\}}{1} = 10 \text{ kg} \tag{8}$$

The final milling was performed in a 36-h time; however, a stop of the process was made at 18 h to take a sample. For both cases, an X-ray analysis was performed, with a scanning speed between 1 and 5°/min, with a step of 0.020°, 40 kW, 40 mAmp, and a sweep between 10° and 100° (**Table 7**). With the 36-h final milling powder, we proceeded to obtain three targets of 25.4-mm diameter, compacting and sintering them later (**Table 8**). In the compaction, a Carver hydraulic press with a maximum load capacity of 12 tons was used. A 10-ton load was applied for 3 min;

Grinding 169 38 40:1 1.7 × 10−2 500 18 Grinding 169 38 40:1 1.7 × 10−2 500 36

**Ratio** *Mballs***/***Mpowders* **Pressure (Torr) Velocity** 

**(rpm)**

Titanium Carbide (TiC) Production by Mechanical Alloying

http://dx.doi.org/10.5772/intechopen.76690

++ +++ + +

++ +++ ++ + +

**Grinding time** 

121

**(h)**

The 5.0-mm thick target was divided into four parts in order to subject it to different sintering temperatures. The first part of the target and, according to the recommendations of Lü and Lai [12], the sample was put into the preheated oven at 700°C and kept at a sustained temperature for 1 h. After that, the oven was turned off and the material was let to cool down to room temperature inside the oven with the door closed. For the second part of the target, the process was repeated at a temperature of 1000°C. The two samples were then removed

in each process, the targets were between 4.5- and 6.5-mm thick.

**Process Initial** 

**powders (g)**

**Temperature (°C)**

**Table 6.** Experimental process details of powders grinding.

from the oven and a visual examination was performed.

18-h grinding TiO<sup>2</sup>

36-h grinding TiO<sup>2</sup>

**Table 7.** Results of X-ray analysis.

**Grinding Composition Abundance**

TiC SiO<sup>3</sup> Al2 O3

TiC SiO<sup>3</sup> Al2 O3 Fe

Convention: +++, abundant (>50%); ++, common (20–40%); ++, poor (10–20%); +, sparse (3–10%).

**Sample Compacted mass material (g) Targets thickness (mm)**

1 10.015 6.5 2 7.751 5.0 3 5.952 4.5

**Table 8.** Compacted mass material and target thickness.

An agitator shaft speed of 300 rpm and a 7-h milling time at an atmospheric pressure was used.

For the milling 3-dry and vacuum, the amount of powder used in the milling was 250 g (**Table 5**). Aluminum powder was added in order to eliminate the formation of CO<sup>2</sup> , to avoid the increase in pressure.

The mass ratio of 40/1 was used. For this case, the ball mass was

$$\frac{M\_{\text{ball}}}{M\_{\text{pural}}} = \frac{40}{1} \implies M\_{\text{ball}} = \frac{(40 \times 0.25 \text{ kg})}{1} = 10 \text{ kg} \tag{9}$$

An agitator shaft speed of 500 rpm and a 12-h milling time were used, and the process was performed in vacuum. In this milling, ethanol was not added to the mixture as a dispersing agent.

From the initial millings, it was determined that the milling time had to be longer, in order to obtain higher concentrations of titanium carbide in the milling; this milling was named final milling. **Table 6** lists the parameters used in the milling.

#### **2.3. Characterization of milling powders**

The powders obtained from millings 1, 2, and 3 were characterized by X-ray diffraction with a Rigaku Rint 2200 diffractometer. The parameters used for X-ray diffraction analysis in millings 1 and 2 were 20 kW, 20 mAmp, and a sweep between 5 and 140° was performed with a scanning speed of 0.2 s/step. The parameters used for the analysis of milling 3 were 40 kW, 40 mAmp, a sweep between 10 and 100°, and a scanning speed of 2 s/step. For milling 3, three samples of material were taken in different parts of the milling container:



**Table 5.** Amount and percentages of the initial powders of the grinding 3, dry grinding, and vacuum grinding.


**Table 6.** Experimental process details of powders grinding.

A mass ratio of 40/1 was used, for which a ball mass was obtained:

= \_\_<sup>40</sup>

The mass ratio of 40/1 was used. For this case, the ball mass was

= \_\_<sup>40</sup>

samples of material were taken in different parts of the milling container:

**Material Percentage (%) Powders mass (g)**

**Table 5.** Amount and percentages of the initial powders of the grinding 3, dry grinding, and vacuum grinding.

Titanium dioxide 62.47 156.2 Graphite 28.13 70.3 Aluminum 9.4 23.5 Total initial powders 100 250

*Mballs Mpowder*

milling. **Table 6** lists the parameters used in the milling.

**2.3. Characterization of milling powders**

**1.** Sample 1: dust adhered to the milling spheres. **2.** Sample 2: dust adhered to the walls of the bowl. **3.** Sample 3: dust adhered to the bottom of the bowl.

<sup>1</sup> <sup>⇒</sup> *Mballs* <sup>=</sup> (<sup>40</sup> <sup>×</sup> 0.5 kg) \_\_\_\_\_\_\_\_\_\_\_\_\_\_

An agitator shaft speed of 300 rpm and a 7-h milling time at an atmospheric pressure was

For the milling 3-dry and vacuum, the amount of powder used in the milling was 250 g (**Table 5**).

<sup>1</sup> <sup>⇒</sup> *Mballs* <sup>=</sup> (<sup>40</sup> <sup>×</sup> 0.25 kg) \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

An agitator shaft speed of 500 rpm and a 12-h milling time were used, and the process was performed in vacuum. In this milling, ethanol was not added to the mixture as a dispersing agent. From the initial millings, it was determined that the milling time had to be longer, in order to obtain higher concentrations of titanium carbide in the milling; this milling was named final

The powders obtained from millings 1, 2, and 3 were characterized by X-ray diffraction with a Rigaku Rint 2200 diffractometer. The parameters used for X-ray diffraction analysis in millings 1 and 2 were 20 kW, 20 mAmp, and a sweep between 5 and 140° was performed with a scanning speed of 0.2 s/step. The parameters used for the analysis of milling 3 were 40 kW, 40 mAmp, a sweep between 10 and 100°, and a scanning speed of 2 s/step. For milling 3, three

Aluminum powder was added in order to eliminate the formation of CO<sup>2</sup>

<sup>1</sup> = 10 kg (8)

<sup>1</sup> = 10 kg (9)

, to avoid the

*Mballs Mpowder*

\_\_\_\_\_\_

\_\_\_\_\_\_

increase in pressure.

used.

120 Powder Technology

The final milling was performed in a 36-h time; however, a stop of the process was made at 18 h to take a sample. For both cases, an X-ray analysis was performed, with a scanning speed between 1 and 5°/min, with a step of 0.020°, 40 kW, 40 mAmp, and a sweep between 10° and 100° (**Table 7**).

With the 36-h final milling powder, we proceeded to obtain three targets of 25.4-mm diameter, compacting and sintering them later (**Table 8**). In the compaction, a Carver hydraulic press with a maximum load capacity of 12 tons was used. A 10-ton load was applied for 3 min; in each process, the targets were between 4.5- and 6.5-mm thick.

The 5.0-mm thick target was divided into four parts in order to subject it to different sintering temperatures. The first part of the target and, according to the recommendations of Lü and Lai [12], the sample was put into the preheated oven at 700°C and kept at a sustained temperature for 1 h. After that, the oven was turned off and the material was let to cool down to room temperature inside the oven with the door closed. For the second part of the target, the process was repeated at a temperature of 1000°C. The two samples were then removed from the oven and a visual examination was performed.


Convention: +++, abundant (>50%); ++, common (20–40%); ++, poor (10–20%); +, sparse (3–10%).

**Table 7.** Results of X-ray analysis.


**Table 8.** Compacted mass material and target thickness.

Scanning electron microscopy (SEM) (JSM-5910LV) tests were performed on the powder material with a 36-h milling time and the material sintered at 1000°C to determine size, distribution, particle shape, and local chemical composition.
