Corrosion products and microstructure of copper alloy

Electronic Supplementary Material - Micrchemical Journal

Corrosion products and microstructure of copper alloy coins from the Byzantine-period Ma‘agan Mikhael B shipwreck, Israel A. Inberg(1), D. Ashkenazi(2)*, M. Cohen(3), N. Iddan(4) and D. Cvikel(3)

(1) School of Electrical Engineering, Tel Aviv University, Ramat Aviv 6997801, Israel. (2) School of Mechanical Engineering, Tel Aviv University, Ramat Aviv 6997801, Israel. (3) Leon Recanati Institute for Maritime Studies and Department of Maritime Civilizations, University of Haifa, Haifa 3498838, Israel. (4) Materials Laboratory, Israel Electric Corporation, Haifa 3508510, Israel.

*Corresponding author. School of Mechanical Engineering, Tel Aviv University, Ramat Aviv 6997801, Israel. E-mail address: [email protected] (Dr. D. Ashkenazi).

1

Fig. 1S. The Ma‘agan Mikhael B shipwreck in its marine environment (Photo: A. Yurman).

2

Fig. 2S. The reverse of coin no. 120.1: (a) the coin’s surface, with some black concretion remains (multi-focal LM); (b) higher magnification of the surface, showing green and brown oxides and some exposed metal (multi-focal LM); (c) the coin’s surface: bright area rich with lead, darker area rich with copper, and black concretion remains at the centre of image (SEM, BSE mode); and (d) higher magnification of the surface, with ground metal at the upper part of the image (SE mode).

3

Fig. 3S. The black graded concretion coating removed from coin no. 120.1: (a) general view of the external side of the concretion (multi-focal LM); (b) higher magnification of the external concretion layer (multi-focal LM); (c) the external concretion layer (SEM, BSE mode); (d) the internal concretion general view (multi-focal LM); (e) higher magnification of the internal concretion layer, showing black, blue, dark grey, light grey-white oxide colours (multi-focal LM); and (f) general view of the internal concretion coating (SEM, BSE mode).

4

Fig. 4S. The internal part of the concretion coating removed from coin no. 120.1 (SEM): (a) general view (SE mode); (b) general view (BSE mode); (c) the needles shown in Fig. 4Sb (BSE mode, arrow); and (d) higher magnification the needles examined by EDS analysis (BSE mode).

5

Fig. 5S. Coin no. 120.2: (a) the surface with dark concretion remains at the left side of image (side B, no grinding, multi-focal LM); (b) the surface near the perimeter of the coin, bright area rich with lead and dark area rich with copper (side A, SEM, BSE mode, ground metal at the right side of image); (c) the surface with bright area rich with lead and dark area rich with copper (side B, no grinding SEM, BSE mode); and (d) the rough surface topography (no grinding, SEM, SE mode).

6

Fig. 6S. Coin no. 120.3, side A: (a) dark concretion (lower part of image) and area of exposed metal (bright upper part of image) (multi-focal LM); (b) the black concretion coating (multi-focal LM); (c) the external surface of exposed metal and some remains concretion (multi-focal LM); and (d) dark concretion (lower part of image) and area of exposed metal (upper part of image), where the bright area is rich with lead (SEM, BSE mode).

7

Fig. 7S. SEM images of coin no. 120.4 (side B, after chemical treatment cleaning): (a) exposed metal with radial cracks pattern at the centre of the coin (BSE mode); (b) higher magnification of the radial cracks pattern (BSE); (c) the metal surface near the radial cracks (BSE mode); and (d) higher magnification of the bright area rich with Pb according to the EDS analysis (BSE mode).

8

Fig. 8S. Coin no. 120.5 (side A): (a) area of exposed metal near the perimeter (multi-focal LM); (b) area of exposed metal at the left side of image and area of a brown-green oxide at the right side of image (multi-focal LM); (c) higher magnification of the exposed metal; and (d) area of exposed metal (no grinding, SEM, BSE mode).

9

Fig. 9S. Multi-focal LM images of coins nos. 132 and 141, showing: (a) the surface of coin no. 132 (side A) with composite black concretion remains at its left and metal at the right (b) coin no. 132 (side B), the interface between the black concretion remains and brown-green oxide with some exposed shiny orange metal; (c) coin no. 141 (side A), black concretion remains and orangecoloured metal with brown oxide; and (d) rough surface of orange-coloured metal and brown oxide (coin no. 141, side A).

10

Table 1S. Weight and dimensions of the seven coins. The dimensions of the coins were measured with a digital caliper. Coin number and description

Weight (g)

Diameter (mm)

Thickness (mm)

120.1 (after mechanical removal of the black concretion coating)

0.66

13.01×13.86

0.94

120.2, including minor remains of the black concretion layer

0.71

13.63

0.89

120.3, including the black concretion layer

2.66

16.95

2.95

120.4, including the black concretion layer

1.64

14.88

2.38

120.4, after the removal of the concretion layer

0.81

13.20

0.96

120.5 (after mechanical removal of the black concretion coating)

0.23

13.29

0.55

132, including minor remains of the black concretion layer

0.62

12.50

0.68

141, including the remains of the black concretion layer

0.97

14.63×17.41

2.66

Table 2S. XRF chemical analysis of the metal of the coins (after cleaning their surface by sandblasting and ethanol) and of the concretion coating of the coins. Coin no. 120.1, obverse, metal covered with oxide layer (average of four measured areas) 120.1, reverse, metal covered with oxide layer, Fig. 2Sb (average of four measured areas) 120.1, internal part of the dark concretion, Fig. 3Sd–e 120.1, external part of the dark concretion, Fig. 3Sa–b 120.2, side A, exposed orange metal and thin oxide layer (average of four measured areas) 120.2, side B, exposed orange metal and thin oxide layer (average of four measured areas) 120.3, side A, exposed metal and thin oxide layer (average of two measured areas)

Cu

Pb

Composition weight percentage (wt %) Sn Zn As Sb Ag Si S

87.2

6.6

3.9

0.1

0.7

–

0.5

0.9

–

0.1

–

84.1

8.8

3.8

0.1

0.8

0.1

0.7

1.3

0.2

0.1

–

58.2 17.7

2.7

–

3.6

0.6

1.6

0.6

14.6

0.4

–

60.6

0.1

0.1

0.1

0.1

0.1

0.4

18.6 19.5

0.3

0.1

74.5 20.3

1.2

–

1.2

0.1

0.7

0.6

1.3

0.1

–

76.2 18.5

1.1

0.1

1.1

0.1

0.7

1.3

0.8

0.1

–

71.1 10.1

1.7

0.5

–

–

0.1

10.0

6.3

0.2

–

11

Fe

Mg

Coin no. 120.3, side A, external dark concretion Fig. 6Sb (average of three measured areas) 120.3, side B, external dark concretion (average of three measured areas) 120.4, side A, metal surrounded by dark concretion 120.4, side A, external dark concretion (average of two measured areas) 120.4, side B, external dark concretion (average of two measured areas) 120.5, side A, Fig. 8Sa (average of three measured areas) 120.5, side B (average of three measured areas) 132, side A, shiny metallic orange surface, Fig. 9Sa (average of four measured areas) 132, side B, shiny metallic orange surface, Fig. 9Sb (average of four measured areas) 132, side B, internal dark concretion (average of three measured areas) 132, side B, external dark concretion, Fig. 9Sb (average of four measured areas) 141, side A, shiny metallic orange surface, Fig. 9Sc (average of three areas) 141, side A, thick brown oxide, external surface, Fig. 9Sd (average of two areas) 141, side B, dark concretion, external surface

Cu

Pb

Composition weight percentage (wt %) Sn Zn As Sb Ag Si S

67.4

0.5

0.1

0.1

–

–

–

69.4

0.4

–

0.1

–

–

–

62.5

0.8

0.4

–

–

–

56.8

2.0

0.3

–

–

55.9

0.8

0.2

0.1

89.2

4.7

2.5

89.1

4.8

91.4

89.8

Fe

Mg

12.7 19.1

0.1

–

4.2

25.8

0.1

–

0.2

16.8 18.7

0.6

–

–

0.2

19.6 20.5

0.6

–

0.1

–

0.1

20.6 21.5

0.7

–

0.1

1.5

0.2

0.7

0.7

–

0.4

–

2.5

0.1

1.6

0.1

0.7

0.5

0.2

0.4

–

2.0

3.5

0.1

0.4

0.1

0.4

1.9

0.1

0.1

–

4.0

3.5

0.1

0.4

–

0.4

1.7

–

0.1

–

36.5 50.6

8.5

–

2.2

–

0.4

–

1.8

–

–

55.1

1.8

0.7

0.1

0.2

–

0.4

26.0

2.3

0.1

13.3

77.8 16.2

1.7

0.1

0.8

0.1

0.5

2.7

–

0.1

–

65.8

0.3

0.1

0.1

0.1

–

0.2

8.6

24.6

0.2

–

58.1

–

–

–

–

–

0.1

17.9 23.7

0.2

–

12

Table 3S. SEM-EDS analysis of the coins, before and after grinding (SA = scanned area). Each coin was scanned at various magnifications of areas from 1000 m × 1000 m to 10 m × 10 m in order to obtain the heterogeneity of each object. Coin no. 120.1, obverse (metal with oxide, no grinding, average of two areas, each SA: 600 m×600 m) 120.1, obverse (metal with oxide, no grinding, SA: 100 m×100 m) 120.1, obverse (exposed metal and thin oxide, SA: 1000 m×1000 m) 120.1, obverse (ground metal, average of two areas, each SA: 100 m×100 m) 120.1, reverse (centre of coin, metal, no grinding, SA: 100 m×100 m) 120.1, reverse (ground metal, average of three areas, each SA: 15 m×15 m) 120.1, external black concretion (Fig. 3Sc, area 1, SA: 800 m×800 m) 120.1, external black concretion (Fig. 3Sc, area 2, SA: 800 m×800 m) 120.1, internal black concretion (Fig. 3Sf

Cu

Composition weight percentage (wt %) As Ag O Si S Fe Cl Al

Pb

Sn

35.1 22.7

6.9

–

1.4

23.7

1.4

2.2

0.3

4.0

32.9 27.6

6.1

–

–

25.2

0.9

5.6

–

33.9 25.2

8.3

–

1.4

20.0

1.2

3.8

49.8 36.8 11.5

–

1.9

–

–

34.2 20.7 10.5

–

1.8

25.1

96.5

–

1.6

–

–

24.3

–

–

–

22.1

–

–

5.1

23.9 35.2

Ca

Mg

C

1.0

1.3

–

–

–

0.5

1.2

–

–

–

5.1

–

1.1

–

–

–

–

–

–

–

–

–

1.4

–

–

4.7

0.8

0.8

–

–

1.7

–

0.2

–

–

–

–

–

–

–

28.1

4.8

10.0

0.7

–

0.8

6.4

0.4

24.5

–

–

29.4

8.4

8.8

0.4

–

0.6

4.6

0.2

25.5

1.7

–

7.9

–

16.7

–

–

–

–

–

9.5

13

Coin no. area 1, SA: 800 m×800 m) 120.1, internal black concretion (Fig. 4Sa–b, area 2, SA: 250 m×250 m) 120.1, internal black concretion (needles, Fig. 4Sc-d, area 2, SA: 50 m×50 m) 120.2, side A (dark ground metal according to BSE mode, SA: 150 m×150 m) 120.2, side A (bright ground metal according to BSE mode, near perimeter, SA: 15 m×15 m) 120.2, side B (bright metal according to BSE mode, no grinding, SA: 300 m×300 m) 120.3, side A (ground metal near perimeter, Fig. 6Sd, upper right side of image SA: 50 m×50 m) 120.3, metallographic sample, T-CS (metal, SA: 50 m×50 m) 120.3, metallographic sample, T-CS (bright metal area according to BSE mode, SA: 10 m×10 m)

Pb

Sn


29.9 27.9

2.1

2.1

–

6.1

–

18.7

–

–

Cu

Ca

Mg

C

–

–

–

13.2

57.5

–

–

0.6

0.7

4.2

–

17.1

–

–

–

–

–

19.9

87.6

6.3

1.4

0.7

1.2

1.8

–

–

–

1.0

–

–

–

–

6.2

65.1

4.7

–

–

13.5

–

–

–

10.5

–

–

–

–

7.3

65.7

2.5

–

–

10.1

–

7.1

–

7.3

–

–

–

–

88.8

4.5

2.4

–

–

1.4

–

0.8

–

–

2.1

–

–

–

86.1

3.6

6.0

0.2

0.3

2.5

–

0.1

0.1

1.1

–

–

–

–

52.6 25.6

4.4

1.5

–

5.5

0.8

–

–

9.6

–

–

–

–

14

Coin no. 120.4, side A, ground metal, SA: 50 m×50 m) 120.4, side A (exposed metal after chemical treatment cleaning, area 1, SA: 500 m×500 m) 120.4, side A (exposed metal after chemical treatment cleaning, area 2, SA: 800 m×800 m) 120.4, side A (exposed metal after chemical treatment cleaning, area 3, SA: 80 m×80 m) 120.4, side B (exposed metal after chemical treatment cleaning, Fig. 7Sa, SA: 500 m×500 m) 120.4, side B (exposed metal after chemical treatment cleaning, bright area 1, Fig. 7Sd, SA: 10 m×10 m) 120.4, side B (exposed metal, bright area 2, Fig. 7Sd, SA: 10 m×10 m) 120.4, external black concretion (SA: 500 m×500 m) 120.4, external black concretion matrix (area 1, SA: 100 m×100 m) 120.4, external black concretion

Cu


Pb

Sn

78.5 12.9

2.7

–

–

4.1

–

–

–

1.8

Ca

Mg

C

–

–

–

–

92.3

4.5

–

0.5

2.7

–

–

–

–

–

–

–

–

–

90.1

4.5

1.4

0.2

2.9

–

–

–

0.9

–

–

–

–

–

96.3

2.2

1.0

–

–

–

–

–

0.5

–

–

–

–

–

89.3

5.9

1.3

–

2.8

–

–

–

0.7

–

–

–

–

–

15.7 38.1

–

–

46.2

–

–

–

–

–

–

–

–

–

23.9 55.3

–

–

20.8

–

–

–

–

–

–

–

–

–

25.2

–

0.9

0.5

–

28.0

5.4

11.2

1.3

0.5

1.1

3.6

0.5

21.8

29.8

3.9

0.8

–

–

27.3

3.5

11.7

2.0

0.6

1.3

2.1

0.5

16.5

35.6

–

–

0.3

–

21.9

4.0

14.7

1.8

0.4

0.7

1.0

0.4

19.2

15

Coin no.

Cu Pb matrix (area 2, SA: 50 m×50 m) 120.4, internal black concretion (SA: 200 20.4 25.4 m×200 m) 120.4, internal black concretion (bright 5.9 46.8 area 1, SA: 100 m×100 m) 120.4, internal black concretion (bright 2.8 52.6 area 2, SA: 20 m×20 m) 120.5, side A (exposed metal, no grinding (Fig. 8Sd, 72.2 – average of two areas, each SA: 50 m×50 m) 120.5, side A (ground metal near 94.1 – perimeter, SA: 150 m×150 m)

Sn


Ca

Mg

C

4.4

–

–

30.0

–

8.2

–

–

–

–

–

11.6

–

–

–

27.3

0.5

–

–

–

–

–

–

19.5

–

–

–

28.4

0.5

–

–

–

–

0.7

–

15.0

5.3

1.3

1.5

13.5

1.1

2.2

0.5

0.9

0.5

1.0

–

–

3.4

–

–

2.5

–

–

–

–

–

–

–

–

Figure Captions 1S. The Ma‘agan Mikhael B shipwreck in its marine environment (Photo: A. Yurman). 2S. The reverse of coin no. 120.1: (a) the coin’s surface, with some black concretion remains (multi-focal LM); (b) higher magnification of the surface, showing green and brown oxides and some exposed metal (multi-focal LM); (c) the coin’s surface: bright area rich with lead, darker area rich with copper, and black concretion remains at the centre of image (SEM, BSE mode); and (d) higher magnification of the surface, with ground metal at the upper part of the image (SE mode). 3S. The black graded concretion coating removed from coin no. 120.1: (a) general view of the external side of the concretion (multi-focal LM); (b) higher magnification of the external concretion layer (multi-focal LM); (c) the external concretion layer (SEM, BSE mode); (d) the internal concretion general view (multi-focal LM); (e) higher magnification of the internal

16

concretion layer, showing black, blue, dark grey, light grey-white oxide colours (multi-focal LM); and (f) general view of the internal concretion coating (SEM, BSE mode). 4S. The internal part of the concretion coating removed from coin no. 120.1 (SEM): (a) general view (SE mode); (b) general view (BSE mode); (c) the needles shown in Fig. 4Sb (BSE mode, arrow); and (d) higher magnification the needles examined by EDS analysis (BSE mode). 5S. Coin no. 120.2: (a) the surface with dark concretion remains at the left side of image (side B, no grinding, multi-focal LM); (b) the surface near the perimeter of the coin, bright area rich with lead and dark area rich with copper (side A, SEM, BSE mode, ground metal at the right side of image); (c) the surface with bright area rich with lead and dark area rich with copper (side B, no grinding SEM, BSE mode); and (d) the rough surface topography (no grinding, SEM, SE mode). 6S. Coin no. 120.3, side A: (a) dark concretion (lower part of image) and area of exposed metal (bright upper part of image) (multi-focal LM); (b) the black concretion coating (multi-focal LM); (c) the external surface of exposed metal and some remains concretion (multi-focal LM); and (d) dark concretion (lower part of image) and area of exposed metal (upper part of image), where the bright area is rich with lead (ESE, BSE mode). 7S. SEM images of coin no. 120.4 (side B, after chemical treatment cleaning): (a) exposed metal with radial cracks pattern at the centre of the coin (BSE mode); (b) higher magnification of the radial cracks pattern (BSE); (c) the metal surface near the radial cracks (BSE mode); and (d) higher magnification of the bright area rich with Pb according to the EDS analysis (BSE mode). 8S. Coin no. 120.5 (side A): (a) area of exposed metal near the perimeter (multi-focal LM); (b) area of exposed metal at the left side of image and area of a brown-green oxide at the right side of image (multi-focal LM); (c) higher magnification of the exposed metal; and (d) area of exposed metal (no grinding, SEM, BSE mode). 9S. Multi-focal LM images of coins nos. 132 and 141, showing: (a) the surface of coin no. 132 (side A) with composite black concretion remains at its left and metal at the right (b) coin no. 132 (side B), the interface between the black concretion remains and brown-green oxide with some exposed shiny orange metal; (c) coin no. 141 (side A), black concretion remains and orangecoloured metal with brown oxide; and (d) rough surface of orange-coloured metal and brown oxide (coin no. 141, side A).

17

Table Captions 1S. Weight and dimensions of the seven coins. The dimensions of the coins were measured with a digital caliper. 2S. XRF chemical analysis of the metal of the coins (after cleaning their surface by sandblasting and ethanol) and of the concretion coating of the coins. 3S. SEM-EDS analysis of the coins, before and after grinding (SA = scanned area). Each coin was scanned at various magnifications of areas from 1000 m × 1000 m to 10 m × 10 m in order to obtain the heterogeneity of each object.

18