PSI - Issue 41

A.M. Ignatova et al. / Procedia Structural Integrity 41 (2022) 527–534 Ignatova A.M., Vereschagin V.I., Naimark O.B./ Structural Integrity Procedia 00 (2019) 000–000

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Table 2. Characteristics of the structure of cast samples of glass-ceramic materials of spinel-pyroxene composition.

Cooling rate, °С/hour

Crystallization zone

Average spinel size, µm

Maximum spinel size, µm

Distribution density of spinels, ꞏ10 -4 units/µm 2

Mode 1

Mode 2

Mode 1

Mode 2

Mode 1

Mode 2

Mode 1

Mode 2

Zone of direct contact with air Transition zone between air cooling and casting center Zone without contact with the external environment Transition zone between the center of the casting and the zone of contact with the mold wall Zone of direct contact with the mold

9.185

11.33

70.06

59.39

8.72

4.42

45

110

11.42

10.94

72.69

64.47

5.93

5.97

30

50

11.75

11.55

98.12

73.62

7.26

5.93

15

35

11.75

12.27

65.88

70.11

6.27

4.98

30

50

12.25

11.64

59.90

75.26

4.44

4.38

25

90

General average

11.27

11.55

73.33

68.57

6.52

5.14

29

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The length of zones varies as follows: in the first crystallization mode, when the average cooling rate was lower, the length of the zone of direct contact with air was 2.5 times less than the same zone in the more aggressive mode. In the case of slower cooling, the transition zone between the air cooling and casting center appeared to be about two times longer than in the case of more non-equilibrium cooling. The zone without contact with the external environment also appeared to be 2.3 times longer in the case of milder mode than in the case of more non-equilibrium mode. The transition zone between zone without contact and zone of contact with the mold has approximately the same length as the same zone in a more aggressive mode; however, in the more aggressive cooling mode, its position has shifted due to the shortening of the previous zone. The zone of contact with the mold is 2.2 times longer in case of more intense cooling than in the milder mode. The simplified versions of the diagrams describing the process of crystallization in cast glass-ceramic materials of spinel-pyroxene type are shown in Fig. 4.

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