질화규소 세라믹 씰링 링 가공의 어려움은 무엇입니까?

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실리콘 질화물 세라믹 씰링 링, as the core component of modern high-end mechanical seals, is known as the “hard core technology” in the sealing field. It perfectly solves the pain points of short service life and easy leakage of traditional metal seals under harsh working conditions such as high speed, high temperature, and strong corrosion, thanks to its excellent wear resistance, self-lubricating properties, high hardness, corrosion resistance, and excellent thermal stability. However, it is precisely these outstanding properties that make it a representative material that is difficult to process.

What problems have been solved by silicon nitride ceramic sealing rings?
Before delving into the difficulties of processing, we first need to understand why such difficult materials are used at any cost. The silicon nitride sealing ring mainly solves the following key problems:

1. Wear resistance and lifespan issues: Traditional hard alloy or silicon carbide sealing rings still suffer from wear in equipment such as high-speed pumps, compressors, and chemical process pumps. Silicon nitride has higher hardness and wear resistance, which can double the service life of the sealing ring and reduce the number of maintenance shutdowns.
2. Dry friction and emergency working conditions: Silicon nitride has excellent self-lubricating properties and high thermal shock resistance. In emergency situations such as sudden water outage or dry operation, the metal seal will instantly lock and burn out, while the silicon nitride sealing ring can withstand it briefly, winning valuable time for the safe shutdown of the system.
3. Strong corrosive medium problem: In corrosive media such as strong acids and alkalis, most metals and even some silicon carbide materials will corrode. Silicon nitride ceramics have extremely stable chemical properties and can work stably in such environments for a long time.
4. Lightweight and high-speed issues: The density of silicon nitride is much lower than that of metals. After being made into a sealing ring, the inertia of the rotating parts is smaller, which is beneficial for the equipment to achieve higher speeds and faster responses, while reducing startup power consumption.
   It is these irreplaceable advantages that make overcoming their processing difficulties crucial.

The core processing difficulties of silicon nitride ceramic sealing rings
The manufacturing process of silicon nitride ceramic sealing rings mainly includes four stages: powder preparation → forming → sintering → precision machining, each stage is full of challenges.
Challenge 1: Material Preparation and Sintering – Obtaining a Perfect Body is a Prerequisite

1. Powder purity and uniformity: The purity, particle size, and particle size distribution of raw powder directly affect the performance of the final product. Impurities and agglomerates can become sources of internal defects in the product, leading to the formation of cracks during sintering and use.
2. The sintering process is difficult and prone to deformation and cracking
   Shrinkage control: Silicon nitride undergoes significant volume shrinkage (usually 15% -20%) during the sintering process. If the shrinkage is uneven, it will cause the billet to warp, deform, and be directly scrapped.
   Selection of sintering aids: Pure silicon nitride is extremely difficult to densify and sintering aids must be added. The types and proportions of additives need to be precisely controlled, as they can affect the high-temperature performance, corrosion resistance, and dielectric properties of the product.
   The sintering process is demanding: advanced processes such as hot pressing sintering or pressure sintering are usually required, which are carried out at high temperatures (above 1700 ℃) and high pressures (nitrogen atmosphere). The temperature control accuracy and atmosphere uniformity of the kiln are highly required, and any fluctuations may lead to batch defects in the products.
   Result: The goal of this stage is to obtain a “blank ring” with dimensions close to the finished product, dense and defect free interior, and regular shape. This is the foundation of all subsequent precision machining, and a defective blank will make subsequent machining meaningless.

Difficulty 2: Extremely high hardness and brittleness – the “hard bone” in processing
This is the most intuitive and core difficulty in silicon nitride processing. Its hardness is high (second only to diamond and cubic boron nitride), while its brittleness is high, which leads to:

1. Failure of traditional processing methods: Conventional tools for machining metals such as turning, milling, drilling, and grinding will quickly wear out in front of silicon nitride and cannot be cut in at all.
2. Special processing mechanism: The processing of silicon nitride is essentially “brittle fracture removal” rather than “plastic deformation removal” of the metal. It is necessary to use high hardness abrasive particles to micro crush and peel the material at high speed. This requires processing equipment to have high rigidity and stability.
3. High cost of cutting tools: Only diamond tools (such as diamond grinding wheels, diamond drill bits, diamond grinding paste) can be used for grinding, grinding, and polishing. Diamond tools themselves are expensive and subject to wear and tear.

Difficulty 3: Precision Dimensional and Geometric Tolerance Control – Competition at the Micron Level
The sealing effect of a sealing ring directly depends on the flatness, parallelism, surface roughness, and dimensional accuracy of its end face and inner and outer diameters. These tolerances are typically required at the micrometer level (μ m).

1. Control of grinding stage: How to stably achieve a dimensional tolerance of ± 0.001mm on high hardness materials during flat grinding and external/internal grinding is the ultimate test of machine tool accuracy, fixture design, and grinding process parameters. Excessive processing pressure or improper craftsmanship can easily cause edge breakage (edge damage).
2. Deformation and stress: Even after sintering, residual stresses may still exist inside the material. During the processing, improper control of grinding heat or uneven material removal can release or generate new stresses, leading to slight deformation of the product after processing or use, and damaging the sealing surface.

Difficulty 4: Ultra precision surface processing (polishing) – achieving “mirror” sealing
The surface roughness requirement for the sealing end face is extremely high (usually requiring Ra<0.01 μ m) to achieve fluid dynamic pressure effect and long-term sealing between the end faces. This is one of the most technologically advanced links in the entire processing chain.

1. Balance between efficiency and quality: Due to its extremely high hardness, its polishing efficiency is very low. Increasing pressure or speed to improve efficiency can easily lead to subsurface damage such as scratches and microcracks.
2. Avoid sub surface damage: These invisible microcracks will propagate under alternating loads and medium pressures, ultimately leading to the fracture and failure of the sealing end face, which is one of the main reasons for the early failure of the sealing ring.
3. Process complexity: Multiple processes are required, from rough polishing to fine polishing, using diamond grinding paste of different particle sizes, combined with specialized polishing solution and polishing pad, on a precision polishing machine. There are strict requirements for the cleanliness, temperature, and humidity of the environment.

Difficulty 5: Cost Control and Consistency – A Major Test of Industrialization

1. High overall cost: High raw material costs, long sintering cycles, expensive diamond tool wear and tear, extremely low processing efficiency, and high scrap rates collectively drive up the final cost of a single silicon nitride sealing ring.
2. Batch stability: Ensuring that the performance of each batch and each product is stable and consistent is a challenge that must be addressed in large-scale production. From powder to sintering, and to every processing step, a strict process control system needs to be established.

Processing silicon nitride ceramic sealing rings is a comprehensive challenge that runs through materials science, mechanical engineering, and process control. It requires manufacturers not only to have a deep understanding of the material properties of silicon nitride, but also to possess exquisite sintering technology and ultra precision machining capabilities. Every perfectly delivered silicon nitride sealing ring is a difficult balance of the “impossible triangle” of “high precision, high consistency, and low cost”.
Despite numerous challenges, with the advancement of sintering technology, the development of CNC precision grinding and polishing equipment, and the continuous accumulation of processing experience, the processing yield and efficiency of silicon nitride ceramic sealing rings are gradually improving. The equipment reliability improvement, maintenance cost reduction, and comprehensive economic benefits it can bring make its application in high-end industrial fields increasingly widespread and irreplaceable. Overcoming these difficulties is a key step in promoting the development of high-end equipment manufacturing industry.

브루드세 세라믹 는 알루미나 세라믹, 지르코니아 세라믹, 질화 규소 세라믹, 질화 알루미늄 세라믹, 실리콘 카바이드 세라믹, 탄화 붕소 세라믹, 바이오 세라믹, 기계 가공 가능 세라믹 등 다양한 고품질 석영 유리를 공급 및 판매합니다. 다양한 세라믹 제품의 맞춤형 요구 사항을 충족할 수 있습니다.