Sintering test

The samples used in the study comprised various biomasses and a selection of Danish straws. The analyses of the fiiels used in the study are presented in Tables 1 and 3, and the chemical composition of ash, together with a summary of the thermobalance sintering tests, in Tables 2 and 4. The Danish wheat straw qualities were selected on the basis of growth site, fertilising and weathering conditions [9],... 

Table 4 Ash chemical composition (wt% dry), and ash sintering test results (Sint75o = sintering degree at 750 °C, 1 bar of steam, Sintgjo sintering degree at 850 °C, 1 bar of...

The object of this paper is the application of thermal analysis techniques, such as DTA/TGA, and sintering tests performed in a muffle furnace, in combination with SEM-EDX analysis techniques, to deepen our understanding of the high-teroperattu e of the ash of various solid biofiicls. 

Two different thermal methods were used for the analysis of the high-temperature behavior of the various ash san5>Ies, i.e., simultaneous DTA/TGA using a NETSCH STA 429 friermal analysis instrument, and sintering tests performed in a simple muffle furnace, both in combination with a SEM/EDX technique for the elemental analysis of the thermally treated ash samples, using a JEOL 6300 scaiming microscope. 

In the case of the DTA/TGA method, the ash samples were placed in a kaolin sarrgrle holder and gradually heated at a lO-C/min rate up to the level of 1000 C. The STA instrument was connected to a PC to generate plots of weight loss and temperature vs. time. For the sintering tests, the ash samples were placed into 25-mL porcelain crucibles and gradually heated from 600 to 1000 C, at 50-100 C intervals, and for periods of 1 b each time, while the physical state and weight of the samples were monitored at the end of each time interval. 

Table 3 Sintering tests of the various biomass ash samples.

In the case of com cob, the results of the sintering tests (Table 3), in combination with those from the SEM-EDX analysis of the thermally treated ash samples, are in full agreement with the results obtained by the DTA-TGA thermal analysis method, clearly showing that mdiing/sintering effects begin at around 750 C or even at lower temperatures. 

In order for sintering tests to accurately predict actual behavior it is necessary that tests be conducted with ash produced under representative furnace conditions (time-temperature history). Fouling behavior is often greatly influenced by sodium reactions. Sodium which vaporizes in the furnace can condense in downstream convection sections thereby concentrating on flyash surfaces. Particle surface reactions are primarily responsible for convection deposit bonding. 

Although iron oxide derived from the nitrate was among the most active materials in the two low-temperature tests, it was the least active in the sintering test. Its low-temperature reactivity had led to a partial sintering of the powder into hard agglomerates which were subsequently impossible to sinter to reasonably dense materials. Conversely, the oxides prepared at higher temperatures, such as from sulfates, sintered well but were less reactive at the temperatures below their formation temperature. That potential low-temperature reactivity had been consumed during formation. 

Iron ore fines, limestone, dolomite, calcined lime, BF return fines and coke breeze were used and pot grate sintering experiments were carried out. Table I gives the chemical composition of the raw materials in the pot grate sintering test. The size distribution of raw material is shown in Table II. The raw material consists of iron ore fines, limestone, dolomite, calcined lime, BF return fines, coke breeze and sinter return fines. Table III shows the proportion of raw material. 

A Pyrex micro filter (Fig. XII, 2, 18) of 8 ml. capacity and furnished with a sintered glass disc is useful for the filtration of hot or boihng hquids. The long cylindrical tube reduces evaporation. The filter may be inserted into a test-tube with side arm (Fig. XII, 2, 13) and the filtrate collected in a centrifuge tube or semimicro test-tube receiver. 

Testing. Chemical analyses are done on all manufactured abrasives, as well as physical tests such as sieve analyses, specific gravity, impact strength, and loose poured density (a rough measure of particle shape). Special abrasives such as sintered sol—gel aluminas require more sophisticated tests such as electron microscope measurement of a-alumina crystal si2e, and indentation microhardness. 

Exposure to PTFE can arise from ingestion, skin contact, or inhalation. The polymer has no irritating effect to the skin, and test animals fed with the sintered polymer have not shown adverse reactions. Dust generated by grinding the resin also has no effect on test animals. Formation of toxic products is unlikely. Only the heated polymer is a source of a possible health hazard (120). 

Brinell Tests of Steel Products Comparison Hardness Tester Practice Rockwell Test on Cemented Carbides Rockwell Test for Sintered Materials Knoop Test for Electrodeposited Coatings Webster Hardness Gauge Barcol Test of Aluminum Alloys... 

Filtered-Particle Inspection. Solids containing extensive inteiconnected porosity, eg, sintered metallic or fired ceramic bodies formed of particles that ate typically of 0.15-mm (100-mesh) screen size, are not inspectable by normal Hquid penetrant methods. The preferred test medium consists of a suspension of dyed soHd particles, which may be contained in a Hquid vehicle dyed with a different color. Test indications can form wherever suspensions can enter cracks and other discontinuities open to the surface and be absorbed in porous material along interior crack walls. The soHd particles that form test indications ate removed by filtration along the line of the crack at the surface where they form color or fluorescent indications visible under near-ultraviolet light (1,3). 

A clear solution can be obtained more quickly, and incidentally the transfer can be made more satisfactorily, by rapidly filtering the solution through a sintered glass funnel with exclusion of carbon dioxide with the aid of the apparatus shown in Fig. 10.9. It is advisable to calibrate the test-tube in approximately 5 mL intervals and to put the graduations on a thin slip of paper gummed to the outside of the tube. 

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