Use of a material sample, in particular a pure iron sample

Abstract

Use of a pure iron sample to ensure that the desired heating of a sintering furnace for dental material is achieved up to a temperature required for sintering the dental material between 1500°C and 1600°C, by checking whether the pure iron sample, after being placed in a sintering bowl of the sintering furnace intended for receiving dental material in the sintering furnace and possibly filled with sintering beads, and after the furnace has been heated to the temperature specified by a user on the dental furnace for sintering the dental material, has melted or melts.

Description

[0001] The invention relates to the use of a material sample, in particular a pure iron sample.

[0002] The integration of CAD / CAM technologies in dentistry has further revolutionized the processing and manufacturing of zyrconium oxide dental prostheses, leading to wider acceptance and application in the industry. The addition of yttrium stabilized the material, improved its toughness and strength, and thus made it a preferred material in dental technology.

[0003] The dental sintering furnaces used in this process play a crucial role in ensuring quality, and the dental sintering furnace is equipped with: - an evacuable combustion chamber (1) with an inlet opening (2) for introducing a sintered object, - a base (3) for receiving the sinter project in a sintering shell

[0004] During sintering, the ceramic material must be heated to a temperature of approximately 1550°C, resulting in higher fusion and higher density.

[0005] The sintering furnace used in this process must maintain a precise and constant temperature to ensure that the sintered object meets the desired quality requirements in terms of strength and durability.

[0006] The required temperature is in the range of approximately 1500 to 1550°C. The correct temperature is crucial for the quality of the sintered object. Excessive temperature can lead to reduced stability and decreased translucency.

[0007] Too low a temperature results in the particles in the material not bonding together sufficiently, which deteriorates the mechanical properties, surface quality and therefore also the aesthetics.

[0008] Most yttrium oxide-stabilized zirconia materials achieve their ideal physical, mechanical and aesthetic properties at about 1550°C.

[0009] Therefore, the correct sintering temperature in the sintering furnace used is of great importance.

[0010] Checking the combustion chamber temperature is not possible for the user / technician in the laboratory, as this requires expertise in measurement technology and the necessary measuring instruments are not available.

[0011] To verify the measuring voltage output, displayed, and used for temperature control by the integrated thermocouple (4), a qualified testing laboratory is required. This is a time-consuming and costly process. Thermocouples (4) measure the temperature at a specific location, which provides no information about the temperature at the location of the sintered object. This object is located in sintering trays (5) filled with sinter beads (6), and up to two or more of these trays are stacked on top of each other for a single sintering process.

[0012] For the established testing procedure using HTH-type PTCR control rings for the temperature range of 1450 °C to 1750 °C, a special micrometer is required to determine the corresponding diameter, which is in the micrometer range, for temperature measurement. Standard micrometers do not provide accurate results. Such a testing procedure does not guarantee reliable quality assurance. Handling such precise measuring instruments requires expertise in metrology and regular, documented calibration of the micrometer by a certified testing laboratory. When using PTCR control rings, it is also recommended to prevent dust formation from abrasion, avoid inhaling dust, prevent contact with the eyes, and dispose of the dust in accordance with local regulations.

[0013] To avoid all these disadvantages, the invention proposes the use of a rod made of 99.9% pure iron, in particular with a diameter of at least 2 mm and a length of at least 20 mm, for temperature testing, which is inserted into the sintering shell 5, which may be filled with sinter beads.

[0014] Pure iron (7) with a purity of 99.9% has a melting point of 1538 °C.

[0015] The change of state, such as the melting of a metal, is one of the most accurate methods for determining temperature. Assessing the melting result allows the technician to visually verify temperature control and whether the required temperature has been reached.

[0016] The pure iron sample can be used to carry out a test procedure as follows: 1. Add the pure iron rod (7) to each sintering process and each sintering tray (5) and start the sintering program with sintered parts. This also makes it possible to include the test result as proof of quality with the sintered objects. 2. To do this, place the pure iron rod (7) in the sintering bowl and start a sintering program without sintering objects at a predetermined temperature of approximately 20 - 30 °C below the melting point of 1538 °C. The final temperature should be maintained for 2-3 minutes.

[0017] Three possible states of the pure iron rod result: 1. The pure iron rod (7) has not melted. This means that the melting temperature was not reached. 2. The pure iron rod (7) is slightly melted and shows a molten surface. This means the melting temperature has almost been reached. This state is also known as the dropping point and indicates that the transition from the solid to the liquid state has been reached. This means the temperature is fine. 3. The pure iron rod (7) has melted. This means that the melting temperature has been reached or even exceeded. In this case, the test procedure must be repeated with a lower adjustable final temperature. If necessary, the specified values ​​can then be adjusted.

[0018] This also makes it possible to assign the sintering result to the sintered object as proof of quality.

[0019] By using a pure iron sample according to the invention, the technician can check the sintering temperature in his device in order to comply with the sintering temperatures specified by the manufacturer of the zirconia materials and thus achieve the ideal physical, mechanical and aesthetic properties.

[0020] The invention also provides valuable assistance to engineers in the practical application of sintering in one or more stacked sintering trays. If one or more pure iron bars are used in each layer, this provides information not only about the melting temperature but also about the temperature and heat distribution in the individual layers of the stacked sintering trays.

[0021] Sintering furnaces can be tested in the same way with regard to heating to temperatures other than the melting point of pure iron. The drawing shows an example of a sintering furnace. In the description above, the reference numerals given in the drawing are used for the individual elements of the sintering furnace.

[0022] The invention proposes the use of a material sample for a temperature testing method, enabling the technician in the laboratory to visually assess the temperature behavior of their sintering furnace in order to achieve the physical, mechanical, and aesthetic quality properties specified by the manufacturer of the zirconia materials. Due to the high temperatures up to 1550°C, the furnace components, such as heating elements (8) and thermocouples (4), are subjected to high stresses and therefore require constant monitoring of their functional properties.

[0023] This testing method can be applied during an ongoing sintering program, either with sintered objects to assess the sintering results or without sintered objects to assess the achieved sintering temperature. It is an inexpensive testing method that can be performed without specialized knowledge of measurement technology or complex measuring equipment, and can be carried out completely without gaps in the process.

Claims

[1] Use of a pure iron sample to ensure that the desired heating of a sintering furnace for dental material is achieved up to a temperature required for sintering the dental material between 1500°C and 1600°C, by checking whether the pure iron sample, after being placed in a sintering dish of the sintering furnace provided for receiving dental material in the sintering furnace and possibly filled with sinter beads, and after heating it to the temperature specified by a user on the dental furnace for sintering the dental material, has melted or melts. [2] Use according to claim 1 for accuracy testing and ensuring the reliability and durability of a sintering process at a temperature equal to the melting point of pure iron. [3] Use of a material sample having a melting point equal to the temperature for sintering material, in particular dental material, in a sintering furnace, to ensure that the desired heating of a sintering furnace is achieved up to a temperature required for sintering the material, in particular between 1500°C and 1600°C, by checking whether the material sample has melted or melts after being placed in the sintering furnace, in particular in a sintering tray of the sintering furnace provided for receiving dental material in the sintering furnace and possibly filled with sintering beads, and after the sintering furnace has been heated to the temperature specified by a user at the sintering furnace for sintering the material. [4] Use according to claim 2 for accuracy testing and ensuring the reliability and durability of a sintering process at a temperature equal to the melting point of the material sample used.

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