Needle coke quality identification

Needle coke, as a high-purity carbon material, plays a key role in new energy, metallurgy, chemical industry and other fields. In lithium battery manufacturing, it is used as anode material to improve battery energy density and cycle life; in the field of electric furnace steelmaking, it is used to prepare high-power electrodes to ensure smelting efficiency and stability; in the chemical industry, it can be used as a catalyst carrier to optimize the chemical reaction process. Compared with ordinary coke, needle coke occupies an irreplaceable position in the high-end materials industry chain due to its high purity, low sulfur content, excellent electrical conductivity and thermal stability. It is an important basic raw material for promoting new energy technology innovation and traditional industrial upgrading.

As the market demand for needle coke surges, quality dispute cases occur frequently. The core of the judicial dispute focuses on: whether the product meets the chemical composition (such as carbon content, sulfur impurities), physical performance indicators (such as resistivity, density), and microstructural requirements stipulated in the contract; whether there is a production accident or product failure due to quality defects; and the definition of liability and loss compensation, etc. In such cases, needle coke quality identification has become the key to resolving disputes. Scientific testing methods are used to quantify product quality, provide technical support for judicial decisions, and ensure fair transactions and standardized development of the industry.

Zhongke Testing is a product quality appraisal service organization registered with the court. It can provide needle coke quality appraisal services. It has a professional appraisal team and advanced instruments and equipment to provide fair and accurate appraisal results for needle coke quality appraisal.

The quality appraisal of needle coke covers the following technical methods:

1. Appearance inspection: Visually observe the appearance of needle coke to check whether there are cracks, holes, impurities and other defects.

2. Chemical composition analysis: Use spectral analysis, chemical titration and other methods to accurately determine the content of carbon, sulfur, silicon, iron and other elements in needle coke.

3. Physical performance testing: Test physical indicators such as density, resistivity, and bending strength to reflect the physical characteristics of needle coke.

4. Microstructure observation: Use a metallographic microscope to observe the needle coke and analyze its crystal structure, internal defects and inclusion distribution.

Applicant Company A and respondent Company B signed a "Purchase Contract for Needle Coke for Lithium Battery Anodes", stipulating that Company B would supply 200 tons of "high-density needle coke" to Company A. After Company A used this material for the production of graphite electrodes, it discovered that some batches of products had problems such as abnormal expansion and substandard true density, resulting in cracking and scrapping of the finished electrodes. Company A claimed that the needle coke had quality defects and claimed economic losses; Company B argued that the problem was caused by Company A’s improper calcination process. After the negotiation between the two parties failed, the case was brought to court, and the court entrusted a third-party appraisal agency to conduct appraisal.

identification and analysis results:

The quality analysis expert group tested and analyzed the contract technical agreement, production process records and sealed samples of "needle coke" and made the following quality analysis opinions:

1, the needle coke involved There are 5-15μm cracks inside the coke body (contract ≤3μm), which directly affects the mechanical properties of the material;

2, the OI value 2.1 of the needle coke involved is far lower than the ≥3.5 required by the agreement (industry standard QI value is usually ≥3.0), indicating that the graphitization structure of the coke body is incomplete, which is directly related to the excessive electrode expansion coefficient (4.8×10⁻⁶/℃).

Needle coke quality appraisal report should include the following content:

1. Information of the appraisal client and the appraised party.

2. Testing items, sampling methods, testing methods and equipment.

3. Test results and analysis.

4. Quality evaluation conclusion.