XRF (X-ray Fluorescence Spectrometry) is a chemical analysis tool commonly used for the quality control of raw materials and finished products in many industries including cement, mining and industrial minerals. The capabilities of XRF instrumentation have advanced significantly in the past decade in both sensitivity and stability such that they are no longer the most important source of error in an analysis. Sample preparation is now by far the most significant source of error in the analysis of materials by XRF. Viewed from this perspective, it is clear that high quality sample preparation techniques and practices are the key to achieving consistent and reliable analytical results.One of the most common methods of preparing samples for XRF analysis is by making pressed pellets. This process is particularly popular as it produces high quality results, is relatively quick and is a low cost approach.
Sample Preparation for Pressed Pellets
The cement was finely milled and homogenized using 20 wt% of cellulose binder in a Planetary Ball Mill. Then pellets were compressed in aluminium sample cups by using a 15T-30 Ton pellet Press and a 40 mm PMP Quick Release Die.The resulting pellet or tablet is then ready for analysis.
First, considering the life of the heating element and the furnace and avoiding the rapid cooling and heating of the furnace, it is recommended not to open the furnace door when the temperature is too high.
In addition, the heating rate of the high-temperature electric furnace is limited, and it is best to set the value below the amount.If it is too large, it will cause the program temperature to rise rapidly, thereby increasing the difference from the actual temperature.At this time, the electric furnace will automatically increase Large heating current will cause the current to be too high. It will cause damage to the program setting module and cause the heating process of the electric furnace to fail. If the temperature is lowered, if the heating resistance wire is not exposed to the outside, there is no problem to open the furnace below 200 degrees ; If the resistance wire is exposed in the heating cavity, it is best to wait until the room temperature is below 100 degrees or even open the furnace door to reduce the damage to the furnace.
And, due to the high temperature inside the furnace, the user is very likely to receive high-intensity heat radiation to cause burns when the furnace door is opened.
Therefore, for safety reasons, we do not recommend users to open the furnace door above 200 degrees under non-essential conditions. If it is necessary to open the furnace door, try to protect it as much as possible, and set the program setting value before the sintering starts, ensure that the program section has been completed when the furnace chamber temperature reaches the setting value, and then open it.
When users use the muffle furnace, there will be some safety hazards due to non-standard operation or failure to operate according to requirements. Henan Chuanghe Laboratory was reminded by the company that the following precautions should be kept in mind when using the muffle furnace:
1.During the sintering process, it is strictly forbidden to open the furnace. Because it is not only dangerous, but the sudden change of temperature may cause damage to the equipment.
2.After sintering is completed, it is not allowed to turn off the power unless it is confirmed that the temperature in the furnace has dropped (below 300 degrees Celsius). Once the cooling fan stops working, the temperature of the device body may rise suddenly, which may cause damage to the device.
3.When first time use or has not been used for a long time. Before re-use, it should be baked at about 120 ℃ for 1 hour, and baked at about 300 ℃ for 2 hours. The sintered sample is placed and used normally.
4.It is forbidden to directly inject various liquids and dissolved metals into the furnace chamber to prevent the liquid from corroding the furnace chamber and heating elements and causing irreparable damage to the furnace.
5.After using the furnace for a period of time, a small crack will occur in the furnace chamber, which is caused by thermal expansion and contraction and is a normal phenomenon.
6.When the cold furnace is used, as the chamber's temperature is low, it needs mount of heat, the heating rate should make sure slow, and the difference in the heating rate of each temperature section is not too large. When setting the heating rate, the physical and chemical properties of the sintered material should be fully considered , So as to avoid spraying and polluting the furnace.
7.Regularly check whether the electrical connection parts of the temperature control system are in good contact, and pay special attention to whether the connection points of the heating elements are tight (the inspection of the heating element connections is about 1 month after the first use, and every 12 intervals thereafter Check once a month).
8.When the silicon carbon rod is used as a heating element, the resistance value will gradually increase after a long time of operation. This phenomenon is called "aging". After the furnace has been in operation for a period of time, due to the aging phenomenon of the silicon carbon rod, the heating rate and ideal temperature of the furnace will not reach the original value. Please adjust the "Maximum Output Percentage" properly and observe that the main current of the ammeter is at an appropriate level. When individual components are damaged due to some reason and need to be replaced, according to the increase in the resistance of other components at that time, select components with appropriate resistance values, and new components cannot be replaced at will. If the components are damaged more or the resistance value increases too much, it is better to replace all the components with new ones when the required furnace temperature cannot be reached;
9.Ensure that the furnace is placed in a safe and stable external environment. Suggestions: 1) The ambient temperature is between -10 and 75 ° C. 2) The relative humidity of the surrounding environment does not exceed 85%. 3) There is no conductive dust, explosive gases and corrosive gases that seriously damage metals and insulating materials around the furnace. 4) There is no obvious tilt, vibration and bumps.
The maintenance and maintenance of equipment requires users to operate in accordance with the operating procedures. During the operation process, personal safety protection must be done to improve safety awareness, check before use, and reasonable repair and maintenance after use.