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A study of corrosion enhanced erosion in Nickel Aluminium Bronze with Niobium and Yttrium
Materials Today: Proceedings xxx (xxxx) xxx
Contents lists available at ScienceDirect
Materials Today: Proceedings journal homepage: www.elsevier.com/locate/matpr
A study of corrosion enhanced erosion in Nickel Aluminium Bronze with Niobium and Yttrium R. Manikandan a,⇑, S.P. Kumaresh Babu b, M. Murali a, A. Vallimanalan a a b
Metallurgical and Materials Engineering, National Institute of Technology, Tiruchirappalli 620015, India Metallurgical and Materials Engineering, National Institute of Technology, Tiruchirappalli 620015, India
a r t i c l e
i n f o
Article history: Received 6 September 2019 Received in revised form 10 October 2019 Accepted 14 October 2019 Available online xxxx Keywords: Nickel Aluminium Bronze Niobium Yttrium Immersion Corrosion enhanced erosion Corrosion rate
a b s t r a c t An investigation was carried in Nickel Aluminium Bronze (NAB) alloyed with Niobium (Nb) and Yttrium (Y) to study the effect of the microstructure for onshore applications. Nickel Aluminium Bronze is broadly used in aqueous atmospheres due to their good mechanical and corrosion resistance properties. The presence of destructive species in aqueous water initiates the corrosion of the engineering modules is inevitable. In-order to optimize the corrosion resistance Nb and Y were added as (1%, 2% & 3%) respectively in the master NAB. The specimens were exposed to the immersion test in NaCl solution. To create the behavior of corrosion and succeeding erosion, altered immersions hours were selected as 8, 16, 24, 32, 40, 48 and 54 h. The mass loss measurements were obtained after the completion of the individual specified time to calculate corrosion rates (CR). Solid particle erosion (SPE) investigations were also carried out on the developed alloys. The size of the particle which is used in the investigation is 50 mm. Corrosion rate was calculated and it is correlated with the immersion time. Scanning electron microscopy (SEM) investigations were observed for the corroded and eroded specimens. Ó 2019 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of the scientific committee of the International conference on Materials and Manufacturing Methods.
1. Introduction Corrosion is the destructive result of chemical reaction between a metal or metal alloys and it surroundings. The consequences of corrosion are certain factors can tend to accelerate the action of a corrosion cell. In the aqueous application, Nickel Aluminium Bronze (NAB) is widely used, more particularly it is used in the propeller blades in-order to reduce the failures. Even though the rate of corrosion is minimize the life time of the component (i.e. propeller blade) made by NAB. Further, minimize the corrosion rate by adding the alloying element like Niobium (Nb) and Yttrium (Y) is added to the NAB in the proportions of 1%, 2% and 3%. During the marine operations of the propeller blade, solid particles entrained in the aqueous solution additional aggravate mass loss at the corrosion sites and this aspect is known as corrosionenhanced erosion. Solid particle erosion is a mechanical degradation process in which material slowly wears away through impact by abrasive particles. While erosion-corrosion involves mechanical ⇑ Corresponding author. E-mail addresses: [email protected] (R. Manikandan), babu@nitt. edu (S.P. Kumaresh Babu), [email protected] (A. Vallimanalan).
wear by solid particles in combination with electrochemical dissolution by the corrosive solution, with both activities occurring concurrently in a dynamic two-phase flow system [1]. Matsumura [2] explains the effect of corrosion on erosion and attributes the enhancement of erosion to the removal of work hardened layer which is caused or accelerated by corrosion attack. Other mechanisms include: i) selective corrosion attack at grain boundaries resulting in enlarged susceptibility of grain removal by erosion [3], and ii) increase in the number of surface defects due to micro-pitting [4]. Previously, many researchers have investigated the erosioncorrosion behavior of steels using various systems, such as rotating electrode systems, flow loop systems, and jet impingement systems. Recently, NAB were studied the erosion-corrosion behavior determined the erosion-enhanced corrosion and corrosionenhanced erosion of their test specimen. The results showed that as the flow velocity increases, erosion becomes a dominating variable in the synergism of the galvanic couple. Hence, the pure erosion and corrosion-enhanced erosion components dominated the overall erosion-corrosion process. In this investigation study, an innovative step is used to study the corrosion-enhanced erosion behavior of NAB with Nb and Y. The test specimens were corroded
https://doi.org/10.1016/j.matpr.2019.10.083 2214-7853/Ó 2019 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of the scientific committee of the International conference on Materials and Manufacturing Methods.
Please cite this article as: R. Manikandan, S. P. Kumaresh Babu, M. Murali et al., A study of corrosion enhanced erosion in Nickel Aluminium Bronze with Niobium and Yttrium, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.10.083
2
R. Manikandan et al. / Materials Today: Proceedings xxx (xxxx) xxx
by immersed in low pH and high chloride environments. As in the next step the specimen was undergone to solid particle erosion. The studies were carried out using SEM in-order to identify the corrosion products and evaluate the material degradation mechanism involved in the corrosion enhanced corrosion process.
corrosion rate was calculated based on the weight loss method using the following Eq. (1). CR ¼
Weight loss ðgÞ 8760 yr1 surface area ðmm2 Þ density ðg=mm3 Þ time ðhr:Þ ð1Þ 3
2. Experimental The chemical composition of the NAB is shown in the Table 1. This alloy is broadly used in onshore and off shore aqueous environments. Cast NAB alloying with Nb and Y in the proportions of 1%, 2% and 3% specimens were immersed in NaCl solution at set temperature 30o C. Immersion test were carried out for Immersion tests were carried out for different times (12 h, 24 h, 36 h, 42 h and 60 h) and the weight loss was measured. Before the tests, specimens of size 30 mm 30 mm 6 mm. After immersion, corroded specimens were carefully rinsed with distilled water, air-dried, and the weight loss was measured. The weight loss method is in accordance with the ASTM G 31-72 immersion test standard. The Table 1 Chemical Composition of the NAB in (wt%). Element
Al
Mn
Fe
Ni
Cu
Composition
10.5
1.05
4.5
4.95
79
Where surface are 900 mm and theoretical density 7.64 103 g/mm3 for NAB was taken for the calculations. Specimens were then for recording their hardness values, a magnitude of 20 mN was selected to measure the hardness of corrosion products. A total of 8 readings were taken for the NAB with Nb and Y and their average value was calculated in Table 2. Surface roughness on corroded and polished specimens was measured under the standard ASME B46. Further, the experiments on corroded surfaces, Air jet erosion tester manufactured by DUCOM under the standard ASTM G76 95 [5]. Particle flow rate (g/min) was precisely controlled by the rotation frequency of the discharge and measuring erodent mass flowing through the nozzle for 10 min at a specified wheel frequency. Impact velocity was measured with an accuracy of ±2 m/s, [6]. Both particle flow rate and impact velocity calibrations were checked after every 10 experiments. Angular shape alumina erodent with particle size of 50 (lm) was deployed in the erosion experiment trails. Erosion tests were carried out on corroded (24 h and 48 h immersed specimens,) as well as un-corroded specimens
Table 2 Brinell hardness values of the specimen. Immersion time (Hr)
NAB NAB NAB NAB NAB NAB
– – – – – –
Nb 1% Nb 2% Nb 3% Y 1% Y 2% Y 3%
Brinell Hardness Number 0
8
16
24
32
40
48
54
Avg.
230.86 289.45 292.45 248.33 267.92 290.45
225.38 297.33 287.58 260.19 292.57 281.34
227.47 301.42 293.66 298.45 287.65 288.15
232.56 348.12 298.47 318.25 301.45 279.54
221.21 326.18 302.45 321.47 311.11 291.68
228.54 318.46 299.45 291.23 318.42 287.41
219.32 312.25 308.68 314.28 301.24 284.65
223.48 321.42 297.31 302.43 294.46 294.24
226.10 314.32 297.50 294.32 296.85 287.18
Fig. 1. SEM images of (a) Nb1% 8Hr, (b) Nb2% 24 Hr, (c) Nb3% 48 Hr (d) Y1% 8 Hr (e) Y2% 24 Hr (f) Y3% 48 Hr.
Please cite this article as: R. Manikandan, S. P. Kumaresh Babu, M. Murali et al., A study of corrosion enhanced erosion in Nickel Aluminium Bronze with Niobium and Yttrium, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.10.083
3
R. Manikandan et al. / Materials Today: Proceedings xxx (xxxx) xxx
Fig. 2. a & b Immersion time vs Mass loss in % and Corrosion rate mm/yr.
Table 3 Corrosion rate and Mass loss for NAB-Nb2%, NAB-Y2%. Immersion time
NAB – Nb 2%
Units
ML (g)
D (g/mm3)
A (mm2)
CR (mm/yr)
ML (g)
NAB – Y 2% D (g/mm3)
A (mm2)
CR (mm/yr)
8 16 24 32 40 48 54
0.82 1.62 2.12 2.64 2.89 3.21 3.15
0.00764 0.00764 0.00764 0.00764 0.00764 0.00764 0.00764
900 900 900 900 900 900 900
130.58 128.99 112.53 105.10 92.04 85.19 74.31
0.76 0.89 1.23 1.61 1.92 2.18 2.11
0.00764 0.00764 0.00764 0.00764 0.00764 0.00764 0.00764
900 900 900 900 900 900 900
121.02 70.86 65.29 64.09 61.15 57.86 49.78
at two different velocities: 30 and 60 m/s. At each impact velocity six different impact angles were used: 15°, 30°, 45°, 60°, 75°, and 90°. Particle flow rate of 3.5 g/min was used in all the erosion tests, which was selected to allow tolerable particle flux on the specimen yet avoiding high inter-particle collisions which are caused by using high particle flow rates [7,8]. Specimens subjected to erosion testing were removed after every 4 min, cleaned and reweighed, repeated for a total time of 20 min. Scanning electron microscopy (SEM) is used to characterize the surface degradation after pure erosion, pure corrosion and erosion enhanced corrosion of NAB with Nb and Y as shown in Fig. 1 & 2.
3. Results The corrosion rate was calculated by the equation with the parameters like weight loss (g) and corrosion rate (CR) in (mm/ yr) as shown in the table in Table 3. From the figure a and b, it is clearly showed that the relationship between the immersion time with the mass loss (%) and the corrosion rate (mm/yr). The above fig is drawn for the alloying percentage of the NAB with Nb2% and NAB with Y2% respectively. In fig a Nab-Nb2% own the mass loss of average is maximum 3.15% in 54 h and minimum in 0.82% in 8 h. As in the same case the mass
Fig. 3. a & b Corrosion enhanced erosion impact velocity at 30 m/s and 60 m/s.
Please cite this article as: R. Manikandan, S. P. Kumaresh Babu, M. Murali et al., A study of corrosion enhanced erosion in Nickel Aluminium Bronze with Niobium and Yttrium, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.10.083
4
R. Manikandan et al. / Materials Today: Proceedings xxx (xxxx) xxx
loss average is minimum 0.76% in 8 h and 2.18% in 48 h. However, the immediate effect of the rate of the corrosion (mm/yr) maximum in 12 h in both cases i.e. NAB-Nb2% and NAB-Y2%. The corrosion rate in the beginning is increase due to the aggressive corrosion attack on surface of the NAB with Nb and Y. 3.1. Corrosion enhanced erosion The selected specimens were undergone a solid particle erosion, the erosion rates were investigated and compared with different velocities as shown in Fig. 3a & b. The impact velocity of the specimen is varied form 30 m/s and 60 m/s. Immersion time for selected as 8 h and the 24 h due to their corrosion rate at the initial stage is high [9–12]. Different angle were used to perform the above experiments. As it is clearly indicated that the relationship between immersion time and the corrosion rate i.e the immersion time is increased the erosion rate is also increased respectively. 4. Discussion Whenever the impact velocity is directly proportional erosion rate is also increased, from 30 m/s and 60 m/s, NAB-Nb 2% at 30o is 0.039 mg/g to 0.028 mg/g in the impact angle 30°. This above said effect is due to the kinetic energy of the particle with high impact velocity. This high impact gives the more contact with the specimen and it produce a large amount of mass loss. The erosion mechanism with respect to the angle from 15° to 90° is varied. More particularly in the composition of the rare earth element with NAB-Y 2% the erosion rate is 0.065 mg/g at 30° to 0.051 mg/g at 45° due to the above said kinetic energy effect and the velocity of the particle. As in the second case of impact velocity of 60 m/s the NAB-Nb2% the erosion rate is 0.038 mg/g at 30° and 0.035 mg/m at 60°. In NAB-Y2% the rate erosion is 0.051 mg/g at 45° to 0.048 mg/g at 60° due to the shear forces incurred on the surface of the material [13–15]. More wear is occurred in the 30 m/s velocity in the NAB-Nb2% and 60 m/s in the NAB-Y2% respectively.
5. Conclusion Investigations were carried out to find the corrosion enhanced erosion characteristics of the NAB-Nb and NAB-Y with the specified impact velocities and different angles. The specimens were immersed in the NACL solution for 8 h to 54 h with the span of 8 h. The differences in the erosion rates of the specimen corroded is relationship with immersion time, in this investigation the corrosion rate is maximum in the beginning due to the sudden attack in the surface of the NAB alloy and corrosion rate recorded for NAB-Nb-2% is 130.58 mm/yr and NAB-2% 121.02 mm/yr. At the end of the analysis it is clearly found that the erosion rate is increased with respect to the solid particle erosion impact jet velocities. This is due to the more amount of shear stress resulting the more amount of mass loss. References [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15]
R.J.K. Wood, 6.09 – Erosion/Corrosion, Compr. Struct. Integr. (2007) 395. M. Matsumura, Corros. Rev. 12 (1994) 321. A. Neville, T. Hodgkiess, H. Xu, Wear 233–235 (1999) 523. R.C. Barik, J.A. Wharton, R.J.K. Wood, K.S. Tan, K.R. Stokes, M. Planck, Wear 259 (2005) 230. ASTM standard, G76-95, Standard practice for conducting erosion tests by solid particle impingement using gas jets, ASTM Standards. 95 (200) 1. A. Ruff, L. Ives, Wear 36 (1975) 195. P.H. Shipway, I.M. Hutchings, Wear 174 (1994) 169. C. Gomes-Ferreira, D. Ciampini, M. Papini, Tribol. Int. 37 (2004) 791. J.R. Laguna-Camacho, A. Marquina-Chávez, J.V. Méndez-Méndez, M. ViteTorres, E.A. Gallardo-Hernández, Wear 301 (2013) 398. J. Malik, I.H. Toor, W.H. Ahmed, Z.M. Gasem, M.A. Habib, R. Ben-Mansour, H.M. Badr, J. Mater. Eng. Perform. 23 (2014) 2274. J. Hu, S. Cao, J. Xie, Anti-Corrosion Methods Mater. 60 (2013) 100. ASTM G 31-72, Standard Practice for Laboratory Immersion Corrosion Testing of Metals, 1999. ASTM G 119 – 04, Standard guide for determining synergism between wear and corrosion, ASTM Standards, 93 (2004) 1 A. Neville, T. Hodgkiess, H. Xu, An electrochemical and micro-structural assessment of erosion—corrosion of cast iron, Wear 233 (1999) 523–534. F. Lin, H. Shao, Effect of impact velocity on slurry erosion and a new design of a slurry erosion tester, Wear 143 (1991) 231–240.
Please cite this article as: R. Manikandan, S. P. Kumaresh Babu, M. Murali et al., A study of corrosion enhanced erosion in Nickel Aluminium Bronze with Niobium and Yttrium, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.10.083
Contents lists available at ScienceDirect
Materials Today: Proceedings journal homepage: www.elsevier.com/locate/matpr
A study of corrosion enhanced erosion in Nickel Aluminium Bronze with Niobium and Yttrium R. Manikandan a,⇑, S.P. Kumaresh Babu b, M. Murali a, A. Vallimanalan a a b
Metallurgical and Materials Engineering, National Institute of Technology, Tiruchirappalli 620015, India Metallurgical and Materials Engineering, National Institute of Technology, Tiruchirappalli 620015, India
a r t i c l e
i n f o
Article history: Received 6 September 2019 Received in revised form 10 October 2019 Accepted 14 October 2019 Available online xxxx Keywords: Nickel Aluminium Bronze Niobium Yttrium Immersion Corrosion enhanced erosion Corrosion rate
a b s t r a c t An investigation was carried in Nickel Aluminium Bronze (NAB) alloyed with Niobium (Nb) and Yttrium (Y) to study the effect of the microstructure for onshore applications. Nickel Aluminium Bronze is broadly used in aqueous atmospheres due to their good mechanical and corrosion resistance properties. The presence of destructive species in aqueous water initiates the corrosion of the engineering modules is inevitable. In-order to optimize the corrosion resistance Nb and Y were added as (1%, 2% & 3%) respectively in the master NAB. The specimens were exposed to the immersion test in NaCl solution. To create the behavior of corrosion and succeeding erosion, altered immersions hours were selected as 8, 16, 24, 32, 40, 48 and 54 h. The mass loss measurements were obtained after the completion of the individual specified time to calculate corrosion rates (CR). Solid particle erosion (SPE) investigations were also carried out on the developed alloys. The size of the particle which is used in the investigation is 50 mm. Corrosion rate was calculated and it is correlated with the immersion time. Scanning electron microscopy (SEM) investigations were observed for the corroded and eroded specimens. Ó 2019 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of the scientific committee of the International conference on Materials and Manufacturing Methods.
1. Introduction Corrosion is the destructive result of chemical reaction between a metal or metal alloys and it surroundings. The consequences of corrosion are certain factors can tend to accelerate the action of a corrosion cell. In the aqueous application, Nickel Aluminium Bronze (NAB) is widely used, more particularly it is used in the propeller blades in-order to reduce the failures. Even though the rate of corrosion is minimize the life time of the component (i.e. propeller blade) made by NAB. Further, minimize the corrosion rate by adding the alloying element like Niobium (Nb) and Yttrium (Y) is added to the NAB in the proportions of 1%, 2% and 3%. During the marine operations of the propeller blade, solid particles entrained in the aqueous solution additional aggravate mass loss at the corrosion sites and this aspect is known as corrosionenhanced erosion. Solid particle erosion is a mechanical degradation process in which material slowly wears away through impact by abrasive particles. While erosion-corrosion involves mechanical ⇑ Corresponding author. E-mail addresses: [email protected] (R. Manikandan), babu@nitt. edu (S.P. Kumaresh Babu), [email protected] (A. Vallimanalan).
wear by solid particles in combination with electrochemical dissolution by the corrosive solution, with both activities occurring concurrently in a dynamic two-phase flow system [1]. Matsumura [2] explains the effect of corrosion on erosion and attributes the enhancement of erosion to the removal of work hardened layer which is caused or accelerated by corrosion attack. Other mechanisms include: i) selective corrosion attack at grain boundaries resulting in enlarged susceptibility of grain removal by erosion [3], and ii) increase in the number of surface defects due to micro-pitting [4]. Previously, many researchers have investigated the erosioncorrosion behavior of steels using various systems, such as rotating electrode systems, flow loop systems, and jet impingement systems. Recently, NAB were studied the erosion-corrosion behavior determined the erosion-enhanced corrosion and corrosionenhanced erosion of their test specimen. The results showed that as the flow velocity increases, erosion becomes a dominating variable in the synergism of the galvanic couple. Hence, the pure erosion and corrosion-enhanced erosion components dominated the overall erosion-corrosion process. In this investigation study, an innovative step is used to study the corrosion-enhanced erosion behavior of NAB with Nb and Y. The test specimens were corroded
https://doi.org/10.1016/j.matpr.2019.10.083 2214-7853/Ó 2019 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of the scientific committee of the International conference on Materials and Manufacturing Methods.
Please cite this article as: R. Manikandan, S. P. Kumaresh Babu, M. Murali et al., A study of corrosion enhanced erosion in Nickel Aluminium Bronze with Niobium and Yttrium, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.10.083
2
R. Manikandan et al. / Materials Today: Proceedings xxx (xxxx) xxx
by immersed in low pH and high chloride environments. As in the next step the specimen was undergone to solid particle erosion. The studies were carried out using SEM in-order to identify the corrosion products and evaluate the material degradation mechanism involved in the corrosion enhanced corrosion process.
corrosion rate was calculated based on the weight loss method using the following Eq. (1). CR ¼
Weight loss ðgÞ 8760 yr1 surface area ðmm2 Þ density ðg=mm3 Þ time ðhr:Þ ð1Þ 3
2. Experimental The chemical composition of the NAB is shown in the Table 1. This alloy is broadly used in onshore and off shore aqueous environments. Cast NAB alloying with Nb and Y in the proportions of 1%, 2% and 3% specimens were immersed in NaCl solution at set temperature 30o C. Immersion test were carried out for Immersion tests were carried out for different times (12 h, 24 h, 36 h, 42 h and 60 h) and the weight loss was measured. Before the tests, specimens of size 30 mm 30 mm 6 mm. After immersion, corroded specimens were carefully rinsed with distilled water, air-dried, and the weight loss was measured. The weight loss method is in accordance with the ASTM G 31-72 immersion test standard. The Table 1 Chemical Composition of the NAB in (wt%). Element
Al
Mn
Fe
Ni
Cu
Composition
10.5
1.05
4.5
4.95
79
Where surface are 900 mm and theoretical density 7.64 103 g/mm3 for NAB was taken for the calculations. Specimens were then for recording their hardness values, a magnitude of 20 mN was selected to measure the hardness of corrosion products. A total of 8 readings were taken for the NAB with Nb and Y and their average value was calculated in Table 2. Surface roughness on corroded and polished specimens was measured under the standard ASME B46. Further, the experiments on corroded surfaces, Air jet erosion tester manufactured by DUCOM under the standard ASTM G76 95 [5]. Particle flow rate (g/min) was precisely controlled by the rotation frequency of the discharge and measuring erodent mass flowing through the nozzle for 10 min at a specified wheel frequency. Impact velocity was measured with an accuracy of ±2 m/s, [6]. Both particle flow rate and impact velocity calibrations were checked after every 10 experiments. Angular shape alumina erodent with particle size of 50 (lm) was deployed in the erosion experiment trails. Erosion tests were carried out on corroded (24 h and 48 h immersed specimens,) as well as un-corroded specimens
Table 2 Brinell hardness values of the specimen. Immersion time (Hr)
NAB NAB NAB NAB NAB NAB
– – – – – –
Nb 1% Nb 2% Nb 3% Y 1% Y 2% Y 3%
Brinell Hardness Number 0
8
16
24
32
40
48
54
Avg.
230.86 289.45 292.45 248.33 267.92 290.45
225.38 297.33 287.58 260.19 292.57 281.34
227.47 301.42 293.66 298.45 287.65 288.15
232.56 348.12 298.47 318.25 301.45 279.54
221.21 326.18 302.45 321.47 311.11 291.68
228.54 318.46 299.45 291.23 318.42 287.41
219.32 312.25 308.68 314.28 301.24 284.65
223.48 321.42 297.31 302.43 294.46 294.24
226.10 314.32 297.50 294.32 296.85 287.18
Fig. 1. SEM images of (a) Nb1% 8Hr, (b) Nb2% 24 Hr, (c) Nb3% 48 Hr (d) Y1% 8 Hr (e) Y2% 24 Hr (f) Y3% 48 Hr.
Please cite this article as: R. Manikandan, S. P. Kumaresh Babu, M. Murali et al., A study of corrosion enhanced erosion in Nickel Aluminium Bronze with Niobium and Yttrium, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.10.083
3
R. Manikandan et al. / Materials Today: Proceedings xxx (xxxx) xxx
Fig. 2. a & b Immersion time vs Mass loss in % and Corrosion rate mm/yr.
Table 3 Corrosion rate and Mass loss for NAB-Nb2%, NAB-Y2%. Immersion time
NAB – Nb 2%
Units
ML (g)
D (g/mm3)
A (mm2)
CR (mm/yr)
ML (g)
NAB – Y 2% D (g/mm3)
A (mm2)
CR (mm/yr)
8 16 24 32 40 48 54
0.82 1.62 2.12 2.64 2.89 3.21 3.15
0.00764 0.00764 0.00764 0.00764 0.00764 0.00764 0.00764
900 900 900 900 900 900 900
130.58 128.99 112.53 105.10 92.04 85.19 74.31
0.76 0.89 1.23 1.61 1.92 2.18 2.11
0.00764 0.00764 0.00764 0.00764 0.00764 0.00764 0.00764
900 900 900 900 900 900 900
121.02 70.86 65.29 64.09 61.15 57.86 49.78
at two different velocities: 30 and 60 m/s. At each impact velocity six different impact angles were used: 15°, 30°, 45°, 60°, 75°, and 90°. Particle flow rate of 3.5 g/min was used in all the erosion tests, which was selected to allow tolerable particle flux on the specimen yet avoiding high inter-particle collisions which are caused by using high particle flow rates [7,8]. Specimens subjected to erosion testing were removed after every 4 min, cleaned and reweighed, repeated for a total time of 20 min. Scanning electron microscopy (SEM) is used to characterize the surface degradation after pure erosion, pure corrosion and erosion enhanced corrosion of NAB with Nb and Y as shown in Fig. 1 & 2.
3. Results The corrosion rate was calculated by the equation with the parameters like weight loss (g) and corrosion rate (CR) in (mm/ yr) as shown in the table in Table 3. From the figure a and b, it is clearly showed that the relationship between the immersion time with the mass loss (%) and the corrosion rate (mm/yr). The above fig is drawn for the alloying percentage of the NAB with Nb2% and NAB with Y2% respectively. In fig a Nab-Nb2% own the mass loss of average is maximum 3.15% in 54 h and minimum in 0.82% in 8 h. As in the same case the mass
Fig. 3. a & b Corrosion enhanced erosion impact velocity at 30 m/s and 60 m/s.
Please cite this article as: R. Manikandan, S. P. Kumaresh Babu, M. Murali et al., A study of corrosion enhanced erosion in Nickel Aluminium Bronze with Niobium and Yttrium, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.10.083
4
R. Manikandan et al. / Materials Today: Proceedings xxx (xxxx) xxx
loss average is minimum 0.76% in 8 h and 2.18% in 48 h. However, the immediate effect of the rate of the corrosion (mm/yr) maximum in 12 h in both cases i.e. NAB-Nb2% and NAB-Y2%. The corrosion rate in the beginning is increase due to the aggressive corrosion attack on surface of the NAB with Nb and Y. 3.1. Corrosion enhanced erosion The selected specimens were undergone a solid particle erosion, the erosion rates were investigated and compared with different velocities as shown in Fig. 3a & b. The impact velocity of the specimen is varied form 30 m/s and 60 m/s. Immersion time for selected as 8 h and the 24 h due to their corrosion rate at the initial stage is high [9–12]. Different angle were used to perform the above experiments. As it is clearly indicated that the relationship between immersion time and the corrosion rate i.e the immersion time is increased the erosion rate is also increased respectively. 4. Discussion Whenever the impact velocity is directly proportional erosion rate is also increased, from 30 m/s and 60 m/s, NAB-Nb 2% at 30o is 0.039 mg/g to 0.028 mg/g in the impact angle 30°. This above said effect is due to the kinetic energy of the particle with high impact velocity. This high impact gives the more contact with the specimen and it produce a large amount of mass loss. The erosion mechanism with respect to the angle from 15° to 90° is varied. More particularly in the composition of the rare earth element with NAB-Y 2% the erosion rate is 0.065 mg/g at 30° to 0.051 mg/g at 45° due to the above said kinetic energy effect and the velocity of the particle. As in the second case of impact velocity of 60 m/s the NAB-Nb2% the erosion rate is 0.038 mg/g at 30° and 0.035 mg/m at 60°. In NAB-Y2% the rate erosion is 0.051 mg/g at 45° to 0.048 mg/g at 60° due to the shear forces incurred on the surface of the material [13–15]. More wear is occurred in the 30 m/s velocity in the NAB-Nb2% and 60 m/s in the NAB-Y2% respectively.
5. Conclusion Investigations were carried out to find the corrosion enhanced erosion characteristics of the NAB-Nb and NAB-Y with the specified impact velocities and different angles. The specimens were immersed in the NACL solution for 8 h to 54 h with the span of 8 h. The differences in the erosion rates of the specimen corroded is relationship with immersion time, in this investigation the corrosion rate is maximum in the beginning due to the sudden attack in the surface of the NAB alloy and corrosion rate recorded for NAB-Nb-2% is 130.58 mm/yr and NAB-2% 121.02 mm/yr. At the end of the analysis it is clearly found that the erosion rate is increased with respect to the solid particle erosion impact jet velocities. This is due to the more amount of shear stress resulting the more amount of mass loss. References [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15]
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Please cite this article as: R. Manikandan, S. P. Kumaresh Babu, M. Murali et al., A study of corrosion enhanced erosion in Nickel Aluminium Bronze with Niobium and Yttrium, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.10.083