**2.4. Titanium deposition on a cast iron layer**

melting and solidification dynamics specific to Ti is that there are no large and visible cracks,

A disadvantage of the dynamics of the phenomenon is that the roughness of the piece is quite high. Studying the BSE (Back Scattered Electrons) image shows the phase difference by the appearance of dark areas and bright areas, when the surface of the base material contains ferrite grains (light color) with darker vermicular areas (carbon), areas found in higher quantity in the center of the "droplet" (carbon forms titanium chemical compound due to chemical activity of carbon in the plasma). The black areas are made up of Ti droplets. The "droplet" area can be divided into three regions characterized by both the variation of the deposition

The first region (**Figure 8a**) represents the center of the "droplet" that received the highest energy impulse in the deposition motion, where the temperature was the maximum, and a melting of the substrate took place. In this area, we do not actually encounter Ti in the form of a microdrop, but just accidentally by slashing. In this area, chemical compounds obtained through the reactions between Ti and the substrate elements predominate, facilitated by the

The second region represents the immediate vicinity area, in the form of an annular shape, and which is a transition zone to the edges of the "droplet". In this area, Ti is found in the form of a compact micromelt, as well as microalloying compounds due to the dynamics of the

In the third zone, which is the periphery of the "droplet," melted and solidified splashes of Ti are predominant; also drops from the melted substrate pulled away the formation site due to the splashing motion. Also, due to the splashing, bumps are formed by microelevation formation right on the edge of the "drop," while in the center, there are flattened areas with

The spreading zone is quite large because Ti and its chemical compounds melt at relatively low temperatures and are in a liquid form, a relatively long time (order of seconds). Due to the

and the layer is relatively compact.

54 Advanced Surface Engineering Research

energy released in the area.

a certain concavity.

form and the variation of the deposition element content.

**Figure 8.** (a) Area distribution of the drop; (b) elemental distribution of the "drop."

melting bath and migrating from the center to the outside.

From micrographs made by scanning electron microscope shall be observed that Ti deposition on cast iron electrode creates a relatively compact layer with limited bumps and obvious cracks. Titanium shall be uniformly deposited both highlighted in **Table 2** by its high percentage and the EDX analysis (**Figure 10**), when is observed the distribution of the titanium deposition on almost the entire surface.

Titanium coatings are compact, as the atomic number of Ti (22) is much closer to that of Fe (26), which means that their atomic radius difference is very small. This makes it easy to transfer the titanium on the substrate. The outer layer of iron underwent a partial melting allowing for titanium microalloying, but mainly the layer is thin, micro interrupted.

Alloying titanium base material is achieved in a smaller extent because of high melting titanium temperature (1800°C) making titanium to quickly solidify once reached the surface. Thus, it explains the presence of areas with excess deposited material (compact undissolved titanium areas into "drop" metal bath and stuck to the surface). At Ti deposition on gray cast

**Figure 9.** Enlarged areas in the SEM image are for highlighting the extent of spreading of the melted area.


**Table 2.** Chemical composition for Ti deposition on cast iron.

In **Figure 11b**, notices zones with microcracks due to the increase of the superficial layer and to the fact substrate is colder than in one-way deposition, so that the cracks are less pronounced. It is also possible that the cracks are only in the first layer and do not get into the second layer.

**Figure 11.** (a) Distribution of Fe, C, and Ti elements for one-way deposition, 500X; (b) distribution of Fe, C, and Ti

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In **Table 3**, it is given the chemical composition of the deposit layer with Ti electrode, one-way deposition. The chemical composition of the deposit layer with Ti electrode, two-way deposition, presents in **Table 4**. Element distribution presents common repartition areas of Fe, C, and Ti, indicating the presence of intermetallic compounds within alloying bath. Microzones with cementite can be seen in the microstructure due to the energy application of the thermal flow and due to the powerful temperature gradient at cooling (the exterior layer cools down quickly). Cooling takes place due to air contact and to the small thickness of the layer (some

The layer thickness, (**Figure 12a**), Ti deposited (one-way deposition) varies between 24.75 and 30.63 μm, indicating a good uniformity of deposition with very small deviations from the

When analyzing the layer thickness (two layers of titanium, **Figure 12b**), it is observed, by examining electron micrographs, that the outer layer of Ti two-way deposition creates a surface as smooth as depositing a Ti layer. The thickness of Ti layer by deposition of two passes

Blanking, titanium deposition (**Figure 13a**) is a thin layer with good adhesion because the rupture is smooth, without exfoliation. The breakage of the layer is similar to a fragile crack due to the higher hardness of the coating over the base material. Analyzing the micrographs

tens of microns).

elements for two-way deposition, 500X.

flatness of the surface and a low roughness.

is uniform and varies between 36.52 and 47.72 μm.

**Figure 10.** (a) SEM microstructure; single layer Ti deposition on cast iron, SE, 500 μm scale; (b) elements distribution by EDX analysis, 60 μm.

iron, the graphite slides do not melt and dissolve in the microzones of the deposition drops. Due to this, the lamellas absorb the heat and release it gradually, keeping the surface warm for a long time, resulting in a more complete distribution of Ti deposited on the surface.

#### **2.5. One-way deposition and two-way deposition using Ti electrode**

In one-way deposition, the deposits with Ti electrode (**Figure 11a**) are compact, due to the atomic number of Ti which is closer to Fe meaning that the difference of atomic radius is very small. This makes titanium transfer easily from interface to substrate. The exterior layer of the ferritic-pearlitic iron stands a partial melting, which made possible titanium micro alloying.

It achieved a thin layer with discontinuous micro zones, without material withdrawals. Titanium has good coating qualities when base material is ferritic-pearlitic iron. The images and the chemical composition of the layer are achieved by means of electronic scanning microscope.

**Figure 11.** (a) Distribution of Fe, C, and Ti elements for one-way deposition, 500X; (b) distribution of Fe, C, and Ti elements for two-way deposition, 500X.

In **Figure 11b**, notices zones with microcracks due to the increase of the superficial layer and to the fact substrate is colder than in one-way deposition, so that the cracks are less pronounced. It is also possible that the cracks are only in the first layer and do not get into the second layer.

In **Table 3**, it is given the chemical composition of the deposit layer with Ti electrode, one-way deposition. The chemical composition of the deposit layer with Ti electrode, two-way deposition, presents in **Table 4**. Element distribution presents common repartition areas of Fe, C, and Ti, indicating the presence of intermetallic compounds within alloying bath. Microzones with cementite can be seen in the microstructure due to the energy application of the thermal flow and due to the powerful temperature gradient at cooling (the exterior layer cools down quickly). Cooling takes place due to air contact and to the small thickness of the layer (some tens of microns).

**Figure 10.** (a) SEM microstructure; single layer Ti deposition on cast iron, SE, 500 μm scale; (b) elements distribution by

iron, the graphite slides do not melt and dissolve in the microzones of the deposition drops. Due to this, the lamellas absorb the heat and release it gradually, keeping the surface warm for a long time, resulting in a more complete distribution of Ti deposited on the surface.

In one-way deposition, the deposits with Ti electrode (**Figure 11a**) are compact, due to the atomic number of Ti which is closer to Fe meaning that the difference of atomic radius is very small. This makes titanium transfer easily from interface to substrate. The exterior layer of the ferritic-pearlitic iron stands a partial melting, which made possible titanium micro alloying. It achieved a thin layer with discontinuous micro zones, without material withdrawals. Titanium has good coating qualities when base material is ferritic-pearlitic iron. The images and the chemical composition of the layer are achieved by means of electronic scanning microscope.

**2.5. One-way deposition and two-way deposition using Ti electrode**

**Element Volume percent, (%) Atomic percent, (%)**

Titanium 76.56 77.64 Iron 22.36 19.44 Carbon 0.46 1.89 Silicon 0.44 0.76 Phosphorus 0.16 0.27

**Table 2.** Chemical composition for Ti deposition on cast iron.

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EDX analysis, 60 μm.

The layer thickness, (**Figure 12a**), Ti deposited (one-way deposition) varies between 24.75 and 30.63 μm, indicating a good uniformity of deposition with very small deviations from the flatness of the surface and a low roughness.

When analyzing the layer thickness (two layers of titanium, **Figure 12b**), it is observed, by examining electron micrographs, that the outer layer of Ti two-way deposition creates a surface as smooth as depositing a Ti layer. The thickness of Ti layer by deposition of two passes is uniform and varies between 36.52 and 47.72 μm.

Blanking, titanium deposition (**Figure 13a**) is a thin layer with good adhesion because the rupture is smooth, without exfoliation. The breakage of the layer is similar to a fragile crack due to the higher hardness of the coating over the base material. Analyzing the micrographs


**Table 3.** Chemical composition of one-way deposition of Ti layer.


**Table 4.** Chemical composition of two-way Ti layer.

carbide alleviates the defects introduced by tungsten by smoothing out surface roughness

**Figure 13.** Distribution of elements in the crack; (a) simple Ti deposition: Ti, Fe, and C; (b) deposition Ti double layer:

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Studying the EDX analysis is observed in the presence of a 32.42% of tungsten and just 13%

A layer thickness analysis was made. It is observed that the triple layer has a relatively even thickness, and the variation of the thickness is proportional with the roughness of the surface. The thickness of the layer varies between 172 and 119 μm (**Figure 14**), meaning that is a relatively thick layer. The surface layer can be grinded, after that also the thickness is relatively

In the fracture, the combination of triple base deposition material presents as a fragile rupture due to the high hardness of the deposited layer. It is noticed that the deposition has not separated, which shows a microalloy with the large diffusion area that creates the adhesion

This ensures the deposited layer a hybrid structure with amorphous feature, containing a layer with deposition elements dissolved in high concentration in basic matrix on a smaller

The analyses were done on multi-layer depositions, namely, tungsten carbide—as the first interface and titanium carbide—as the second interface and tungsten exterior layer (WC/TiC/W), being made with PHI 5000 Versa Probe-XPS X-ray photoelectron spectrometer. The determination of energetic maximum (energetic peaks) gives indications on the chemical compounds

and covering areas with crackers and squeezing of the material.

between the deposited layer and the base material.

**2.7. XPS analysis for the sample with WC/TiC/W deposition**

titanium (**Table 5**) [27].

distance than 100 μm [27].

high [27].

Ti, Fe, and C.

**Figure 12.** (a) Thickness value for depositing one-way deposition Ti layer; (b) thickness for deposition of Ti two-way layer.

obtained in the electronic scanning microscope for two-layer titanium casting test specimen (**Figure 13b**), the deposition and compactness of the layer were observed.

The deposition of titanium in the quartz has a characteristic form of breakage due to the high hardness of the deposited area.

#### **2.6. Ti/W/TiC deposition analysis**

Heterogeneous triple deposition begins by depositing a titanium layer on the surface of the base because it has good adhesion, depositing relatively compact, no gaps, no strong oxide layers, and no massive roughing on the surface of the sample. Titanium has the property of being a good support for mechanical and thermal shocks. The second layer is a tungsten electrode, which is a hard material with a very high melting temperature that creates deposition craters and areas of material gaps but improves the hardness of the deposited layer. Titanium

**Figure 13.** Distribution of elements in the crack; (a) simple Ti deposition: Ti, Fe, and C; (b) deposition Ti double layer: Ti, Fe, and C.

carbide alleviates the defects introduced by tungsten by smoothing out surface roughness and covering areas with crackers and squeezing of the material.

Studying the EDX analysis is observed in the presence of a 32.42% of tungsten and just 13% titanium (**Table 5**) [27].

A layer thickness analysis was made. It is observed that the triple layer has a relatively even thickness, and the variation of the thickness is proportional with the roughness of the surface. The thickness of the layer varies between 172 and 119 μm (**Figure 14**), meaning that is a relatively thick layer. The surface layer can be grinded, after that also the thickness is relatively high [27].

In the fracture, the combination of triple base deposition material presents as a fragile rupture due to the high hardness of the deposited layer. It is noticed that the deposition has not separated, which shows a microalloy with the large diffusion area that creates the adhesion between the deposited layer and the base material.

This ensures the deposited layer a hybrid structure with amorphous feature, containing a layer with deposition elements dissolved in high concentration in basic matrix on a smaller distance than 100 μm [27].

### **2.7. XPS analysis for the sample with WC/TiC/W deposition**

obtained in the electronic scanning microscope for two-layer titanium casting test specimen

**Figure 12.** (a) Thickness value for depositing one-way deposition Ti layer; (b) thickness for deposition of Ti two-way

**Element Iron Carbon Titanium Silicon** Percentage, % 58.82 35.59 3.58 1.99

**Element Iron Carbon Titanium Silicon** Percentage, % 88.32 7.25 2.41 1.99

The deposition of titanium in the quartz has a characteristic form of breakage due to the high

Heterogeneous triple deposition begins by depositing a titanium layer on the surface of the base because it has good adhesion, depositing relatively compact, no gaps, no strong oxide layers, and no massive roughing on the surface of the sample. Titanium has the property of being a good support for mechanical and thermal shocks. The second layer is a tungsten electrode, which is a hard material with a very high melting temperature that creates deposition craters and areas of material gaps but improves the hardness of the deposited layer. Titanium

(**Figure 13b**), the deposition and compactness of the layer were observed.

hardness of the deposited area.

layer.

**2.6. Ti/W/TiC deposition analysis**

**Table 4.** Chemical composition of two-way Ti layer.

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**Table 3.** Chemical composition of one-way deposition of Ti layer.

The analyses were done on multi-layer depositions, namely, tungsten carbide—as the first interface and titanium carbide—as the second interface and tungsten exterior layer (WC/TiC/W), being made with PHI 5000 Versa Probe-XPS X-ray photoelectron spectrometer. The determination of energetic maximum (energetic peaks) gives indications on the chemical compounds

#### 60 Advanced Surface Engineering Research


**Table 5.** Chemical composition of the Ti/W/TiC layer.

• for O1s with the energetic band between 522 and 544 eV local extremes decompose appro-

**Figure 15.** General graph obtained at radiation time for WC/TiC/W deposition at duration of: (a) 16.01 minutes; (b)

**Chemical compound CO2 CO3 TiCN C TiC WC** Energetic maximum (eV) 291.6 290.2 288.7 285.1 281.2 281.1

areas are listed in **Table 7** for each chemical compound in whose composition oxygen

• for Fe2p3, **Table 8**, with the energetic band between 700 and 740 eV, it notices local maxima

• for Ti2p3, **Table 9**, with the energetic band between 450 and 475 eV, emphasizes the local maxima from this energetic range corresponding to the following chemical compounds

• for W4f, **Table 10**, with the energetic band between 25 and 45 eV, emphasizes the local maxima from this energetic range corresponding to the following chemical compounds

The presence of massive amounts of oxides is due to the deposition in air without a protection layer but only with the protection of the plasmatic atmosphere between cathode and. Oxygen

Energetic maximum (eV) 536.7 529.4 531.1 531.1 531.1

Energetic maximum (eV) 715.7 710.7 711.5 711.1 707.1

, TiNO, WO3

, Ti2 O4

O3

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**O4 TiO2 TiNO WO3 Ti2**

**O3 FeOOH FeWO4 FeO Fe3**

. Local energetic maximum

, FeOOH, FeWO4

, FeO,

**O4**

**C**

O4 , TiO2

in the energetic range of the following chemical compounds Fe2

, and TiC, **Figure 16**.

priate to the following oxides Fe2

**Table 6.** Local energetic maximum areas for each compound.

C.

O3

, WO3

**Chemical compound Fe2**

**Chemical compound Fe2**

**Table 7.** Local energetic maximum areas for each compound.

**Table 8.** Local energetic maximum areas for each compound.

, and W.

enters.

32.01 minutes.

Fe3 O4

TiO2

Fe2 (WO4 )3 , WO2

, and Fe3

, TiC, TiN, Ti2

**Figure 14.** Deposition layer thickness Ti/W/TiC; 200 μm.

of that element in the energy area corresponding to the photoelectronic spectrum of kinetic energy. For the sample with WC/TiC/W deposition are presented two graphs generated at different radiation times, the first at 16.01 minutes (**Figure 15a**) and the second at 32.01 minutes (**Figure 15b**). Exposure time was increased to remove the effects of contamination because elements such as Si, P, and Ni appear in small percentages, being elements that occur through absorption on surface during deposition or later on. In general, graphs notice the presence of the chemical elements on the surface as well as the orbitals of each element such as C1s—28.6%, Fe2p3—22.4%, Ti2p—8.1%, and W4f—6.5% and from the atmosphere O1s—30.6% and N1s— 3.1% [28].

The graph with local maxima is presented showing chemical elements and bonds in the energetic range of 0–1200 eV. For each chemical element, the energetic bonds were studied such as the chemical compounds appeared in the layer and so enlarged areas in the energetic scale realized.

• for C1s between 274 and 296 eV. In the area maxima peaks discovered that correspond to the following compounds CO2 , CO3 , TiCN, TiC, WC. Local energetic maximum areas are listed in **Table 6** for each chemical compound in whose composition carbon enters.

**Figure 15.** General graph obtained at radiation time for WC/TiC/W deposition at duration of: (a) 16.01 minutes; (b) 32.01 minutes.


**Table 6.** Local energetic maximum areas for each compound.


The presence of massive amounts of oxides is due to the deposition in air without a protection layer but only with the protection of the plasmatic atmosphere between cathode and. Oxygen


**Table 7.** Local energetic maximum areas for each compound.

of that element in the energy area corresponding to the photoelectronic spectrum of kinetic energy. For the sample with WC/TiC/W deposition are presented two graphs generated at different radiation times, the first at 16.01 minutes (**Figure 15a**) and the second at 32.01 minutes (**Figure 15b**). Exposure time was increased to remove the effects of contamination because elements such as Si, P, and Ni appear in small percentages, being elements that occur through absorption on surface during deposition or later on. In general, graphs notice the presence of the chemical elements on the surface as well as the orbitals of each element such as C1s—28.6%, Fe2p3—22.4%, Ti2p—8.1%, and W4f—6.5% and from the atmosphere O1s—30.6% and N1s—

**Element Iron Carbon Tungsten Titanium** Percentage, % 49.82 4.67 32.41 13.07

**Table 5.** Chemical composition of the Ti/W/TiC layer.

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The graph with local maxima is presented showing chemical elements and bonds in the energetic range of 0–1200 eV. For each chemical element, the energetic bonds were studied such as the chemical compounds appeared in the layer and so enlarged areas in the energetic

• for C1s between 274 and 296 eV. In the area maxima peaks discovered that correspond to

listed in **Table 6** for each chemical compound in whose composition carbon enters.

, TiCN, TiC, WC. Local energetic maximum areas are

, CO3

3.1% [28].

scale realized.

the following compounds CO2

**Figure 14.** Deposition layer thickness Ti/W/TiC; 200 μm.


**Table 8.** Local energetic maximum areas for each compound.


**Table 9.** Local energetic maximum areas for each compound.

The values for thermal conductivities, **Figure 17**, are very different, being much smaller than base material value. Thin layer depositions with Ti and TiC electrodes on base of ferriticpearlitic gray iron create thermal barriers in the deposited piece. Thermal barrier has a positive effect because during functioning, at reduced heating, small dilatations appear, so thermal stresses with high values are not introduced in the piece and decrease the danger of deformation appearance or even thermal fatigue, which leads to piece cracking. One can meet an emphasized blockage of thermal transfer at one-way heterogeneous depositions, due to

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In choosing the method for microhardness determining, it must be taken into consideration layer's structure and properties. For Ti and TiC, W and WC electrodes were made microhardness measurements with Vickers method. PMT3 microhardness machine was used. Pressing weight of the diamond indenter was 50 g (HV50), **Table 12**. The samples were grinded and polished after deposition, and microhardness measurements accomplished due to the small

**Figure 17.** Graphic of thermal conductivity variation for thin layer deposition with vibrating electrode method.

atomic lattice modification, in terms of addition materials and deposition sequence.

**Material Value of thermal conductivity, k (W/m K)**

**Table 11.** Values of thermal conductivity for base material and all kinds of deposition.

Base material 24.41 One-way Ti layer 18.34 Two-way Ti layer 10.59 One-way TiC layer 20.67 Two-way TiC layer 16.70

**2.9. Hardness analysis of the deposit layers**

thickness of the deposit layer.

**Figure 16.** XPS analysis for Ti2p3 at the ferrite pearlite iron sample covered with WC/TiC/W triple layer.


**Table 10.** Local energetic maximum areas for each compound.

and active nitrogen are also present in this atmosphere, as demonstrated by the presence of the compounds such as TiCN, WO2 , WO3 , TiO2 , FeO, Fe2 O3 , Fe3 O4 , FeOOH (rust), TiNO, and Ti2 O3 .

#### **2.8. Thermal conductivity analysis for deposit layers**

Thermal conductivity analysis for deposit layers with vibrating electrode method accomplished with Mathis TCI apparatus [29].

In case of thin layer deposition, some peculiar phenomena appear and conductivity varies in terms of deposit layer nature, deposit technology, number of deposit layer, and layer compactness. Between the properties that influence thermal conductivity, we mention besides porosity degree of the layer, deposition irregularity (drops appearance, material discontinuities, and high roughness), hardness (inverse proportional to conductivity), and thickness of the deposit layers, too, **Table 11**.


**Table 11.** Values of thermal conductivity for base material and all kinds of deposition.

The values for thermal conductivities, **Figure 17**, are very different, being much smaller than base material value. Thin layer depositions with Ti and TiC electrodes on base of ferriticpearlitic gray iron create thermal barriers in the deposited piece. Thermal barrier has a positive effect because during functioning, at reduced heating, small dilatations appear, so thermal stresses with high values are not introduced in the piece and decrease the danger of deformation appearance or even thermal fatigue, which leads to piece cracking. One can meet an emphasized blockage of thermal transfer at one-way heterogeneous depositions, due to atomic lattice modification, in terms of addition materials and deposition sequence.

#### **2.9. Hardness analysis of the deposit layers**

and active nitrogen are also present in this atmosphere, as demonstrated by the presence of

Thermal conductivity analysis for deposit layers with vibrating electrode method accom-

In case of thin layer deposition, some peculiar phenomena appear and conductivity varies in terms of deposit layer nature, deposit technology, number of deposit layer, and layer compactness. Between the properties that influence thermal conductivity, we mention besides porosity degree of the layer, deposition irregularity (drops appearance, material discontinuities, and high roughness), hardness (inverse proportional to conductivity), and thickness of

, FeO, Fe2

**(WO4**

O3 , Fe3 O4

**)3 WO2 WO3 W**

, FeOOH (rust), TiNO, and

**O3 TiC**

, TiO2

Energetic maximum (eV) 36.4 34.1 34.1 31.8

**Figure 16.** XPS analysis for Ti2p3 at the ferrite pearlite iron sample covered with WC/TiC/W triple layer.

, WO3

**Chemical compound TiO2 TiC TiN Ti2**

**Table 9.** Local energetic maximum areas for each compound.

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Energetic maximum (eV) 464.9; 458.4 454.8; 460.1 454.8; 463 455.8 455.1

the compounds such as TiCN, WO2

plished with Mathis TCI apparatus [29].

the deposit layers, too, **Table 11**.

**2.8. Thermal conductivity analysis for deposit layers**

**Chemical compound Fe2**

**Table 10.** Local energetic maximum areas for each compound.

Ti2 O3 . In choosing the method for microhardness determining, it must be taken into consideration layer's structure and properties. For Ti and TiC, W and WC electrodes were made microhardness measurements with Vickers method. PMT3 microhardness machine was used. Pressing weight of the diamond indenter was 50 g (HV50), **Table 12**. The samples were grinded and polished after deposition, and microhardness measurements accomplished due to the small thickness of the deposit layer.

**Figure 17.** Graphic of thermal conductivity variation for thin layer deposition with vibrating electrode method.


TiN, TiNO, and TiCN) in the layer, which explains the mechanical properties of the surface

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The solution is multiple layers, with the advantage to obtain a greater diffusion, which leads

The surface quality resulting from deposition using the pulse electric discharge method is dependent on the quality and chemical composition of the electrode. We used Ti, TiC, W, and WC electrodes, and we can conclude that Ti and TiC create much smoother surfaces than those obtained with W and WC electrodes. Titanium has a good adhesion to the surface of ferrite-perlite iron, creating compact layers, with no major bumps and few microholes. Tungsten "burns" the contact surface due to the high temperatures generated in the electric arc, does not deposit itself on the piece, but only makes superficial quenches. Titanium carbon and tungsten carbide have affinity to the ferrite base matrix creating homogeneous layers but with pronounced cracks due to the coefficient of expansion different from the base material. It notices the influence of the chemical elements from working atmosphere (oxygen and nitrogen), leading to compound formations in the superficial layer. Thus, it notices the presence of

Thermal conductivity of coated surfaces is considerable inferior from the base material. In these conditions, we can conclude that each coating is forming a thermal shield, fact that can be exploited in technical field, in case of using cast-iron for elements that must resist to

From metallurgical aspects point of view, for homogeneous surfaces, we can conclude that tungsten electrodes and tungsten carbide are benefic in increasing the surface hardness.

In order to obtain surfaces with superior qualities, it is possible to combine the method of deposition by impulse discharge with laser treatment or with thermal spraying treatment in order to retrieve the deposited surface in order to obtain more compact layers without cracks

Petrică Vizureanu\*, Manuela-Cristina Perju, Dragoş-Cristian Achiţei and Carmen Nejneru

[1] Wang Y, Ma H, Li X. MATEC Web of Conferences: Interface behavior of tungsten coating on stainless steel by electro spark deposition. 2015;**35**:01006. DOI: 10.1051/matecconf

to a better anchoring for the layer, with no effect on the surface quality.

Fe, Ti, and W oxides as well as complex nitrides and carbides.

thermal shocks: heating systems and burning chambers.

\*Address all correspondence to: peviz2002@yahoo.com "Gheorghe Asachi" Technical University Iasi, Romania

layer (microhardness).

and with low roughness.

**Author details**

**References**

20153501006

**Table 12.** Values of microhardness measurements for deposit layers, HV50.

**Figure 18.** (a) Comparison analysis regarding microhardness for simple and double coatings using Ti and TiC electrodes; (b) comparison analysis regarding microhardness for simple and double coatings using W and WC electrodes.

The indenter acted on sample section, and not on deposit surface, so that values represent only the hardness of the layer and not of the base material. Analyzing **Figure 18a** notices that the microhardness values of the thin layer achieved by vibrating electrode method are close to all types of deposition, but double as value against the value of the base material (ferriticpearlitic iron). Analyzing **Figure 18b** notices that the microhardness values of the thin layer achieved by vibrating electrode method are close to all types of deposition, but double as value against the value of the base material (ferritic-pearlitic iron).
