target, aim at, address, focus on, in response toPM2.5The optimization of particle sampler material to reduce the deviation of particle deposition can be focused onMaterial selection for sampling headStarting from three aspects: surface treatment process and structural anti adsorption design, combined with JuchuangJCH-120F-1The technical characteristics of the type sampler are proposed, and the following optimization schemes are proposed:

1、 Sample head material upgrade: aluminum alloy substrate+Inert coating

1. The natural advantages of aluminum alloy substrate

JuchuangJCH-120F-1The type sampler has adopted aluminum alloy material as the main body of the sampling head, which has the advantages of:

Antistatic performance: Low surface resistivity of aluminum alloy（≤106Ω）It can effectively reduce the electrostatic adsorption caused by friction during the sampling process. The experiment shows that the aluminum alloy sampling head operates in a dry environment (relative humidity)30%）The sedimentation deviation of particulate matter is reduced compared to plastic materials40%.

Thermal stability: Aluminum alloy has high thermal conductivity（237W/m·K）In high-temperature environments (such as summer field sampling), the surface temperature of the sampling head has a small temperature difference from the airflow, avoiding particle rebound or uneven deposition caused by thermal expansion.

Mechanical strength: Aluminum alloy hardness（HB≥120）It is much higher than plastic and can withstand the impact during transportation or installation of the sampler, preventing deformation of the sampling head and causing turbulence in the airflow.

2. Surface coating optimization

To further reduce particle deposition, the following coatings can be added to the surface of aluminum alloy:

Polytetrafluoroethylene（PTFE）Coating: thickness controlled within5-10μmThe surface energy is as low as18-22mN/mReduce the adhesion force between particulate matter and the surface of the sampling head70%A comparative test conducted in a certain laboratory showed that,PTFECoating sampling headPM2.5The loss rate of particulate matter in sampling3.2%drop to0.8%.

Nano silica coating: by sol-gel method-Micro nano structure is formed on the surface of aluminum alloy by gel method to increase the surface roughness（Ra≤0.2μm）Reduce the contact area between particles and the surface. This coating can makePM10Reduction of sampling bias25%Especially suitable for high humidity environments (relative humidity>80%）.

2、 Structural anti adsorption design: streamlined+Anti static interface

1. Streamlined sampling head design

Surface transition optimization: Change the right angled edge of the sampling head entrance toR=5mmThe rounded corners reduce the phenomenon of airflow separation.CFDSimulation shows that streamlined design can reduce the turbulence intensity inside the sampling head30%Improved uniformity of particle deposition15%.

Gradual tube structure: The inlet diameter of the sampling head is designed to beΦ40mmThe outlet diameter gradually decreases toΦ25mm, forming an accelerated airflow (flow rate from5m/sIncrease to12m/s）Using inertia effect to reduce small particles（PM1.0The sedimentation below. Experiments have shown that this structure canPM2.5Improved sampling efficiency10%.

2. Anti static interface design

Conductive rubber sealing ring: Conductive rubber (volume resistivity) is used at the connection between the sampling head and the filter membrane clamp≤10³ Omega cm）Introduce static electricity into the sampler casing and ground it to prevent the edge of the filter membrane from adsorbing particles due to static electricity. On site testing shows that conductive rubber interfaces can reduce the deposition of particulate matter at the edge of filter membranes60%.

Metal thread connection: The connection between the sampling head and the sampler body has been changed toM16×1.5Metal thread, contact resistance≤0.1ΩEnsure static conductivity. Compared to plastic threads, metal thread connections can improve the overall anti-static ability of the sampler5Twice.

3、 Environmental adaptability optimization: humidity and temperature control

1. Hydrophobic coating to cope with high humidity

Fluorocarbon resin coating: Spray fluorocarbon resin on the inner wall of the sampling head (contact angle>110°）Make water droplets form spherical rolls on the surface, reducing the impact of humidity on particle deposition. Experiments have shown that under relative humidity90%Under environmental conditions, fluorocarbon resin coating canPM2.5Sampling deviation from15%drop to5%.

Heating module integration: embedded inside the sampling headPTCHeating element (power)5W）When the ambient temperature is below5℃Automatically start and keep the surface temperature of the sampling head higher than the airflow2-3℃To avoid particle adhesion caused by condensation of water vapor. A winter field sampling case shows that the heating module canPM10Improved stability of sampling data30%.

2. Application of temperature compensation materials

Memory alloy bracket: The sampling head support structure adopts nickel titanium alloy (linear expansion coefficient)≤12×10 ⁻⁶/℃）, in-20℃to50℃Dimensional changes in the environment ＜0.02mmTo avoid poor sealing between the sampling head and the filter membrane due to thermal expansion and contraction. Experiments have shown that memory alloy supports can enable samplers toAt extreme temperaturesThe leakage rate under the degree of0.5%drop to0.1%.

4、 Practical cases and effectiveness verification

A provincial environmental monitoring station conducted a comparative test on the optimized sampler:

Test conditions:PM2.5concentration300μg/m³Relative humidity85%, Temperature25℃.

Test results:

Before optimization (uncoated aluminum alloy substrate): particle deposition deviation8.2%Edge loss rate of filter membrane3.5%.

Optimized (aluminum alloy)+PTFEcoating+Streamlined design: Deviation in particle deposition2.1%Edge loss rate of filter membrane0.7%.

Conclusion: Material and structural optimization can improve the overall accuracy of the sampler3Double, satisfiedHJ/T 93-2013Requirements for the first level sampler in the standard (deviation)≤5%）.

Conclusion

Through comprehensive optimization of aluminum alloy substrate upgrade, surface inert coating, streamlined structure, and anti-static interface,PM2.5The sedimentation deviation of particulate matter in particulate matter samplers can be significantly reduced. In the future, with the advancement of nanomaterials and3DThe development of printing technology will lead to the evolution of sampler materials towards lighter weight and higher precision, providing more reliable technical support for air pollution monitoring.