BS EN 993-19-2004 pdf download.Methods of test for dense shaped refractory products Part 19: Determination of thermal expansion by a differential method.
NOTE Arrangements can be made for the upper moving column to be fixed to the furnace, and the combination of furnace and column then forms the moveable loading device In this case, a counter balancing weight will be necessary to achieve the required contact stress.
5.1.4 Two dIscs
Two discs shall be 5 mm to 10 mm thick, at least 50,5 mm in diameter and not less than the actual diameter of the test pieces. The discs shall be of art appropriate refractory material compatible with the material under test
NOTE For example, high fired mullite or alumina for alurnino-silicate products, and magnesia or spinel for basic products.
These discs are placed between the test piece and the fixed and moving columns. The disc placed between the test piece and the fixed column shall have a central bore (see 5.1.5). The ends of the fixed and moving column shall be plane and perpendicular on their axes; the face of each disc shall be plane and parallel
If chemical reaction is expected between discs and test piece, a platinum or platinum/rhodium foil (0,2 mm thickness) shall be placed between them.
5.1.5 Arrangement of the apparatus
The arrangement of the two columns, the two discs, the platinum sheet. if used, and the test piece is shown in
Figure 1 which also shows typical diameters of the bores in the fixed column and the disc between them.
5.1.6 ApplyIng the load
The columns and the discs shall be capable of withstanding the applied load up to the final test temperature without significant deformation. There should be no reaction between the discs and the loading system.
NOTE The material from which the discs are made should have a T, value greater than or equal to the temperature at which the test material has a T5 value. T1 and T5 correspond to temperatures for which the deformation values measured according to EN 993-8 are respectively I % and 5 %.
5.2 Furnace
The furnace (preferably with a vertical axis) shall be capable of raising the temperature of the test piece to the final test temperature at the specified rate (see clause 7) in an atmosphere of air. The temperature of the region of the furnace occupied by the test piece, when at a stable temperature above 500 °C, shall be uniform around the test piece (12,5 mm above and below) to within ± 10 K this shall be verified by carrying out tests using the thermocouples located at different points on the curved surface of the test piece
NOTE The furnace design should be such that the whole of the column assembly can be reached easily, either by movement of the supporting column or, if access into the furnace is restricted, by movement of the furnace itself, The assembly should be such that the test p,ece and loading column stand vertically and co-axial with the support column when unrestrained.
6 Test pieces
The test piece shall be a cylinder 50 mm ± 0,5 mm in diameter and 50 mm ± 0,5 mm in height, with a hole from 12 mm to 13 mm in diameter, extending throughout the height of the test piece, bored co-axially with the outer cylindrical surface.
NOTE 1 The axis of the test piece should preferably be in the direction in which the product was pressed. NOTE 2 When agreed between the parties, other load bearing dimensions can be used in the test.
The top and bottom faces of the test piece shall be made plane and parallel by sawing (and grinding, if necessary), and shall be perpendicular to the axis of the cylinder. Au surfaces of the cylinder shall be free from visible defects. Measurements of the height at any two points, using Vernier calipers (see 5.5) shall not differ by more than 0,2 mm When one face of the test piece is placed on a plane surface and a set square also in contact with the surface is brought into contact with any part of the periphery of the test piece, the gap between the side of the test piece and the square shall not exceed 0,5 mm.
To ensure that the top and bottom ends of the test piece are flat over their entire surface, each end shall in turn be pressed on to a leveling plate which is lined with carbon paper and hard filter paper (0,15 mm in thickness) As an alternative to carbon paper. the ends of the test piece may be inked using a stamp pad. Test pieces that do not show two complete, clearly visible coloured impressions shall be re-ground.
NOTE 3 The flatness of the surface can also be contro’led with a straightedge.
7 Procedure
Measure the height of the test piece to ± 0.1 mm, and measure the inner and outer diameters of the test piece. Set up the test piece between the supporting and loading columns with the spacing discs, and adjust the measuring device to the correct setting. Position the assembly within the furnace.
Apply an actual load to the loading column of such magnitude that the compressive stress caused in the test piece
(including that due to the mass of the loading column) is of 0,01 MPa. The contact load shall not vary by more than
± iN.
NOTE 1 For special purposes, the load can be modified to the actual calculated load in the application field. This should be mentioned in the test report.
Raise the temperature of the furnace to the final test temperature at such a rate that the regulating thermocouple (see 5.4.2) indicates a rise in temperature of 2,5 °Clmin ± 0,5 °C/min.
NOTE 2 For materials exhibiting volumetric phase changes (e.g sica and zirconia), vety slow heating rates can be required to determine the behaviour over the phase change region.BS EN 993-19-2004 pdf download.