*2.2.1 The characterization of ultra-hard 97MXC coatings*

A complete characterization of a deposit requires the most accurate knowledge of its chemical composition, the concentration of various alloying elements or impurities. The chemical composition of the 97MXC deposits was determined by semi-quantitative elementary chemical analysis of EDX type (Energy Dispersive X-ray Spectroscopy). The analysis system used (EDAX-AMETEK, Holland, 2008) is attached to an electron microscope (QUANTA 200 3D, FEI, Holland, 2008), being a microanalysis detector that records the energy of X-rays emitted from the surface of the specimen when scanned with an electron beam. This laboratory investigation allowed us to highlight the types of existing chemical elements and the proportions in which they are present.

To determine the chemical composition of the sprayed hard alloys, each sample measuring 10 mm x 10 mm x 5 mm, was investigated by spot analysis, at 10 different points located on the cross-section. Before being investigated, the samples were metallographically prepared, by sanding on abrasive paper and polishing to remove impurities and oxides formed on the surface of the deposits.

**Table 3** presents the mass percentages of the chemical elements identified in the composition of the ultra-hard deposit - depending on the intensity of the electric current used in the thermal spraying process.

As an example, **Figure 10** presents the EDX spectrum and the mapping (distribution of chemical elements on the scanned surface) of the chemical elements present in the 97MXC layer deposited by arc spray process, at current I = 220A and pressure p = 5.5 bar.

In all the cases (of coatings at different intensities with 97MXC material) on the scanned areas, the following chemical elements were identified following the EDX elemental chemical analysis: Fe, W, Cr, C, O Ni and Ti. Correlating these results with the data in **Table 3**, it had been able to conclude that the concentration of the alloying elements does not show changes due to the increase of the electric current intensity, respectively of the increase of the electric arc temperature.

#### *2.2.2 The XRD analysis of the 97MXC coatings*

The XRD analysis (XRD - X-ray diffraction) is a fast-analytical technique, used primarily for phase identification of a crystalline material. This type of analysis


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**Figure 11.**

*X-ray diffraction patterns of 97MXC coatings.*

**Figure 10.**

*Hard Alloys with High Content of WC and TiC—Deposited by Arc Spraying Process*

is very important because it highlights the existing phases and constituents in the electric arc coated layer. Knowing the phases and constituents can help to understand the coatings behavior during the different types of tests they have been subjected to. The testss were performed using the X'PERT PRO MRD diffractometer (Panalytical, Holland, 2008) with the following working configuration: Cu anode

*EDX spectrum and chemical elements distribution map in case of 97MXC coating (I = 220A, p = 5.5 bar).*

**Figure 11** shows the X-ray diffraction patterns of the 97MXC coatings obtained at a pressure of 6.0 bar, at a spray distance of 110 mm and different intensities of the

From the XRD patterns it is observed that the three coatings contain the Fe-Cr alloy, complex carbides of the FeW3C, Fe3W3C and Fe6W6C type and fractions of

with λ = 1.54 Å, open eulerian cradle sample support, 2θ = 20–90°, [42].

electric current: 200 A - sample Ia, 220 A - sample Ib and 250 A - sample Ic.

*DOI: http://dx.doi.org/10.5772/intechopen.94605*

**Table 3.** *Chemical composition of the ultra-hard coatings (p = 5,5 bar).* *Hard Alloys with High Content of WC and TiC—Deposited by Arc Spraying Process DOI: http://dx.doi.org/10.5772/intechopen.94605*

**Figure 10.** *EDX spectrum and chemical elements distribution map in case of 97MXC coating (I = 220A, p = 5.5 bar).*

is very important because it highlights the existing phases and constituents in the electric arc coated layer. Knowing the phases and constituents can help to understand the coatings behavior during the different types of tests they have been subjected to. The testss were performed using the X'PERT PRO MRD diffractometer (Panalytical, Holland, 2008) with the following working configuration: Cu anode with λ = 1.54 Å, open eulerian cradle sample support, 2θ = 20–90°, [42].

**Figure 11** shows the X-ray diffraction patterns of the 97MXC coatings obtained at a pressure of 6.0 bar, at a spray distance of 110 mm and different intensities of the electric current: 200 A - sample Ia, 220 A - sample Ib and 250 A - sample Ic.

From the XRD patterns it is observed that the three coatings contain the Fe-Cr alloy, complex carbides of the FeW3C, Fe3W3C and Fe6W6C type and fractions of

**Figure 11.** *X-ray diffraction patterns of 97MXC coatings.*

*Welding - Modern Topics*

in which they are present.

pressure p = 5.5 bar.

fication of phases and constituents;

*2.2.1 The characterization of ultra-hard 97MXC coatings*

impurities and oxides formed on the surface of the deposits.

intensity, respectively of the increase of the electric arc temperature.

**Current intensity, (A) Chemical element, (% weight)**

current used in the thermal spraying process.

*2.2.2 The XRD analysis of the 97MXC coatings*

*Chemical composition of the ultra-hard coatings (p = 5,5 bar).*

• elementary chemical composition - necessary to determine the presence and

• structural characterization - necessary for the study of microstructure, identi-

• mechanical characterization - which highlights the mechanical properties of 97MXC coatings: porosity, adhesion, microhardness, wear behavior.

A complete characterization of a deposit requires the most accurate knowledge of its chemical composition, the concentration of various alloying elements or impurities. The chemical composition of the 97MXC deposits was determined by semi-quantitative elementary chemical analysis of EDX type (Energy Dispersive X-ray Spectroscopy). The analysis system used (EDAX-AMETEK, Holland, 2008) is attached to an electron microscope (QUANTA 200 3D, FEI, Holland, 2008), being a microanalysis detector that records the energy of X-rays emitted from the surface of the specimen when scanned with an electron beam. This laboratory investigation allowed us to highlight the types of existing chemical elements and the proportions

To determine the chemical composition of the sprayed hard alloys, each sample measuring 10 mm x 10 mm x 5 mm, was investigated by spot analysis, at 10 different points located on the cross-section. Before being investigated, the samples were metallographically prepared, by sanding on abrasive paper and polishing to remove

**Table 3** presents the mass percentages of the chemical elements identified in the composition of the ultra-hard deposit - depending on the intensity of the electric

As an example, **Figure 10** presents the EDX spectrum and the mapping (distribution of chemical elements on the scanned surface) of the chemical elements present in the 97MXC layer deposited by arc spray process, at current I = 220A and

In all the cases (of coatings at different intensities with 97MXC material) on the scanned areas, the following chemical elements were identified following the EDX elemental chemical analysis: Fe, W, Cr, C, O Ni and Ti. Correlating these results with the data in **Table 3**, it had been able to conclude that the concentration of the alloying elements does not show changes due to the increase of the electric current

The XRD analysis (XRD - X-ray diffraction) is a fast-analytical technique, used primarily for phase identification of a crystalline material. This type of analysis

200 48.67 13.84 13.08 11.43 5.63 4.21 3.14 220 48.89 13.64 12.30 12.10 8.65 3.85 2.57 250 46.42 14.21 12.84 12.42 7.32 3.91 2.88

**Fe W Cr C O Ni Ti**

the proportions of the chemical elements of the analyzed coatings;

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**Table 3.**

FeB, Cr2B, Fe2O3 and Fe3O4. Peaks of WC and W2C are present in all three coatings, formed as a result of decomposition during the thermal spraying process, similar to the results reported by He et al. [43]. In additional to the eutectic phases of WC, W2C and TiC, alloyed solid solutions of γ(Fe, Ni) and γ(Ni, Cr) were also identified. It is noted that the intensity of the W2C peak increases with increasing current intensity. It is also suggested that the high temperature of the electric arc favors the decomposition of the WC carbides into single elements, respectively the formation of C-poor compounds such as W2C.
