EN 820-2 pdf free download

EN 820-2 pdf free download. Advanced technical ceramics – Methods of testing monolithic ceramics – Thermo-mechanical properties – Part 2: Determination of self-loaded deformation.
3 Term and definition For the purposes of this European Standard the following term and definition applies. 3.1 self-loaded deformation the property induced by heat, which results in a ceramic body being readily deformed under its own weight 4 Principle The method involves determining whether or not test bars supported only at their ends deform at a series of temperatures, recording any self-loaded deformation observed, and recording the results graphically. The temperature of commencement of self-loaded deformation, taken from the graph, is reported. This test is intended as a simple method of determining the upper use temperature of ceramic components in a self-loaded condition. The criterion is an upper limit of flexural distortion. The test is suitable for use on furnace construction materials and on any ceramic materials, from which components are subjected to further processing at high temperatures. 5 Apparatus 5.1 Measurement apparatus , of the type shown in Figure 1 . The distance between the knife edge supports shall be 1 60 mm ± 0,5 mm. The gauge for measuring deformation (sag or bow) shall be accurate to 0,01 mm. NOTE The dial gauge shown in Figure 1 is an example only. 5.2 Steel bar, of dimensions as shown in Figure 2, with the top surface flat to ± 0,01 mm and parallel, to ± 0,01 mm, to the under surfaces in the regions of reduced thicknesses. 5.3 Laboratory furnace, capable of achieving 1 600 °C, and of holding the temperature uniformly over the area occupied by the test pieces (see Figure 3) to within ± 5 °C. A controlled atmosphere, other than air, may be used if required. This shall be reported (see clause 1 0). 5.4 Two refractory supports , with square cross-section of approximately 1 2 mm (see Figure 3), made of material which is compatible with the test material at the test temperature. The supports shall be inspected after each firing and where there is evidence of reaction with the test pieces, the supports shall be replaced. 5.5 Thermocouples (two ) , one to control the furnace and one to measure the temperature of the test pieces. The thermocouples shall be either type R, type S or type B in accordance with EN 60584-1 . 6 Test pieces Materials for testing shall be selected in accordance with the guidance given in ENV 1 006. Test pieces shall be rectangular bars, within the following range of dimensions: a) length: 1 73 mm to 1 77 mm; b) width: 1 1 ,5 mm to 1 2,5 mm; c) thickness: 3,9 mm to 4,1 mm. The test pieces shall be ground flat and parallel so that the thickness tolerance of a set of test pieces shall be ± 0,02 mm. NOTE 1 A set is the number of test pieces which are required for the determination of the temperature of commencement of self-loaded deformation. Two pieces are required for each determination at a single temperature. Test pieces may be either cut from fired ceramic products or may be prepared especially for this method of test. NOTE 2 In the latter case they should be fired before testing in a manner comparable to production firing. 7 Procedure 1.1 Setting up of measurement gauge Check that the measurement gauge (see 5.1 ) probe is positioned at the mid-point between the two knife edges, as shown in Figure 1 . Place the steel bar (see 5.2) on the knife edges and adjust the gauge to read zero. 7.2 Marking of the test pieces Mark the upper face of one end of the test piece with refractory paint, as the reference end. Draw a pencil line 8 mm from this reference end, across the top surface of the test piece, to act as a reference marker to be aligned with the knife edge of the reference gauge (see 7.3). Repeat the above procedure for the second test piece.EN 820-2 pdf download.