PTFE and ZnO/PTFE coatings displayed good wear resistance

Superhydrophobic surfaces that mimic surfaces found in nature, such as the lotus leaf, are an attractive research topic in various fields of study because of their numerous applications. More recent studies have focused on superhydrophobic surfaces that reduce or completely stop the accretion of ice and snow on power lines and aircraft that operate in cold regions. The superhydrophobic phenomena is usually achieved by creating a dual-scale roughness that is composed of micro- and nano-scale structures that trap air in-between themselves and reduce the surface energy of the textured surface.

 

The objective of this study was to assess the tribological behavior of micro/nano particle based superhydrophobic coating mixtures composed of PTFE, composite PTFE/PEEK, diatomaceous earth (DE), and composite PTFE/ZnO that can be potential candidates for anti-wetting and anti-icing applications for transportation systems. A contact profilometer was used to measure and characterize the average roughness and thickness of coatings. Coating wettability was assessed by measuring the tangent-line contact angle of static water drops on coated surfaces. Friction and cyclic abrasive wear tests were conducted via ball-on-flat tribometer using a spherical tungsten probe at room temperature. Scanning electron microscopy was used to characterize the physical and chemical properties of the coatings and identify the wear mechanisms.

 

The results showed that all coatings except ZnO/PTFE exhibited superhydrophobicity. Abrasive wear mechanisms were the dominant modes for the coatings. PTFE and ZnO/PTFE coatings displayed good wear resistance, superior to that of the DE and PTFE/PEEK coatings.

 

Study on related properties of ptfe

1.  Properties of polytetrafluoroethylene modified epdm rubber

 EPDM modified by polytetrafluoroethylene (PTFE) and nano silicon dioxide (SiO2) was prepared by vulcanization. Scanning electron microscope and infrared spectrum showed that PTFE and EPDM had good compatibility. DSC test showed that the composite had a unique glass transition temperature. When PTFE is added in 5 parts, PTFE and EPDM have a good compatibility. At this time, mechanical properties of epdm-ptfe reach the highest, and its tensile strength, elongation at break, hardness and tear strength are 22.42mpa, 588.91%, 82.0° and 49.60 kN/m respectively. Thermogravimetric analysis and aging experiments show that the aging and heat resistance of PTFE are improved. The mechanical properties of EPDM were also significantly improved after adding 5 parts of nano SiO2.

 2.  Structure and properties of polytetrafluoroethylene hot-rolled fiber membrane

 PTFE fiber membranes were prepared by hot rolling process and orthogonal design. Scanning electron microscope (SEM) was used to observe the surface morphology of the fiber membrane, and its thickness, permeability, aperture, porosity, tensile properties, acid and alkali corrosion resistance were tested and evaluated. The results showed that PTFE hot-rolled fiber film thickness was 0.12 ~ 0.15 mm, permeability was 80 ~ 101 mm/s, pore diameter was 14 ~ 17 ms, porosity was 14.57% ~ 27.04%, fracture strength was 38 ~ 59 N, elongation at break was 30% ~ 38%.In the 9 kinds of fiber membranes, there are still a lot of fibrous structures except the fiber melting on some surfaces. After acid and alkali treatment, the tensile properties of the fiber membrane remained unchanged. According to the orthogonal test results, the fiber mesh density has the greatest influence on the thickness, permeability, pore diameter and tensile properties of the fiber membrane, and with the increase of fiber mesh density, the permeability and pore diameter of the fiber membrane decrease, while the thickness and fracture strength increase.

 3.  Structure and properties of polytetrafluoroethylene/polypropylene hybrid melt jet filter material

 In order to extend the storage time of static charge on the surface of polypropylene (PP) melt-blown materials, the storage capacity of static charge was improved by organic hybridization. In the experiment, PTFE ultrafine powder and PP slice were mixed to granulate in a certain proportion, and different nonwoven materials were obtained by melt-jet molding process. The structure and performance of the nonwoven materials, such as apparent morphology, micropores, surface electrostatic potential and filtration efficiency, were studied, and external corona electret technology was adopted to make the material surface carry static charge. The test results show that adding PTFE can effectively improve the storage capacity of static charge of melt-jet PP nonwoven materials, and when PTFE mass fraction is 0.1%, the surface static voltage is the highest, the filtration performance is the best and the static charge stability is the best.

 

Introduction of ptfe welding process

Steel lined ptfe equipment is usually made with discharge port, feed port, perspective mirror, etc., but how to successfully apply this kind of pipe port in the complex head intersecting line, of course, our answer is welding, then how to welding?How to control the temperature of ptfe welding?Below we tell one by one.

1, ptfe head pipe mouth production

PTFE pipe welding on sealing head to first of all, we should make PTFE sealing head nozzle, according to the size of the nozzle diameter steel head and according to certain proportion by using powder moulding process manufacturing nozzle, 8 hours of sintered under the 380 plus or minus 5 degrees Celsius, after the completion of the sintering good nozzle with lathe car to the right size, to the congratulations of PTFE tube at this moment you have finished.

2, ptfe head opening

Put the extracted head into the steel head, and use the principle of light transmission to accurately open the head, pay attention to the ptfe head must be consistent with the steel head, or the final equipment is prone to bulge, rupture and other potential hazards.

3, ptfe pipe mouth welding

By the first two steps, we can carry out PTFE welding. Here we know that there are two ways of welding (hot pressure welding and hot air welding). We will explain them one by one.

(1) hot pressure welding

Before hot pressure welding we should know the necessary theoretical knowledge, hot pressure welding is a kind of hot welding, provide sufficient heat and enough pressure.Here, we must ensure that the welding interface temperature must reach 673.15k and the pressure reaches 1-2mpa. Therefore, in order to ensure the welding, we need to make corresponding molds to ensure the successful completion of the thermal pressure welding.When all is done, the FEP film can be welded by pressurizing and heating the interface between the nozzle and the head.

(2) hot air welding

Similarly, ptfe hot air welding is a kind of hot welding, which is much simpler than hot pressure welding and does not require so many molds. After placing the pipe mouth, PFA welding rod and hot air welding gun higher than 713K are used to preheat PFA first and then place it on the welding seam for continuous welding.

Note: whether it's hot pressure welding or hot air welding welding temperature will be higher than the melting point of ptfe, ptfe is possible under the temperature cracking, produces in the process of pyrolysis perfluorinated isobutylene and other poisonous gases, so the welding should be in a ventilation environment, when the condition does not allow such as the four fluorine lining tank welding in production must use the fan air supply air flow assurance and wearing a gas mask to ensure security at the same time.

 

 

What is expanded tetrafluoroethylene seal tape?

Expanded tetrafluoron sealing belt is made of pure Polytetrafluoroethylene dispersion resin, which is stretched at high temperature through lamination.it has low friction coefficient, good resistance to chemical corrosion and airtightness, and can be used at the temperature of -250℃--+280℃ for the sealing of reaction kettle, steam transmission generator and all kinds of special-shaped cans and drums.

 The expanded tetrafluoroethylene sealing tape can be pasted on the flange sealing surface.Flange sealing part under medium and low pressure is an economical and practical sealing material.

 The expanded tetrafluoroethylene sealing belt retains the chemical corrosion resistance of ptfe, and at the same time, it has flexibility, compression strength, excellent creep resistance, cold flow resistance and tensile strength.

 

Production process and application of ptfe film

Ptfe film processing equipment will use a Isostatic Moulding Press Machine, Isostatic Moulding Press Machine production bar, and then sintering, finally using a Skiving Machine for Skiving.

Ptfe films are mainly divided into two types: microporous film and turning film.The biggest difference between the two is the permeability of microporous membrane, which is produced by biaxial stretching.Turning film is cut out of the lathe, it does not breathe.

I do not know about turning film, know that it should be used on the seal more.We're going to talk about microporous membranes.

Polytetrafluoroethylene (ptfe) microporous film is made of polytetrafluoroethylene resin particles, which is expanded and stretched to form a microporous film. It can be divided into the following categories:

 

1. Air filtration membrane

Polytetrafluoroethylene membranes can be used for atmospheric dust removal, air purification and so on the membrane pore size can be controlled 0.2 um, porosity can reach more than 88%, and the needle felt, mechanism of cloth, non-woven fabric, glass fiber and other filter material with surface phase composite filtering performance of coated fabric, PTFE coated filter material has high peel strength, air volume, uniform pore size distribution, etc.As a dust bag or fold type dust removal filter cartridge installed within the dust removal equipment, will be promptly and efficiently calculated intercept with micron ultra fine dust, dust removal efficiency can reach more than 99.99%, the service life for three years, ventilation rate of up to 3-6 m/min, is currently the world's most advanced air filtration material, all kinds of vacuum cleaners, air filter, air purification equipment, the best choice for high efficiency air filter, etc.

Technical parameters are as follows:

Thickness: 5 um - 15 um

Air permeability: 80-100l /㎡•s

Width: 1800 mm or less

Resistance: pa 80 or less

Efficiency: 99.99%

 

2. Waterproof and moisture-permeable microporous membrane

Ptfe waterproof moisture permeable microporous membrane is made and approved by a special process the bidirectional tensile membrane surface per square inch can reach billions of a microporous, each pore diameter (0.5 to 0.1 um um) is less than the minimum water molecules in the mist of the minimum value (20 UN um - 100), the diameter greater than the water vapor molecules (0.0004 to 0.0003 um um), the water vapor through the water, and cannot pass, take advantage of the microporous structure can achieve excellent waterproof and moisture permeable function;In addition, because the hole is extremely small and longitudinal irregular bending arrangement, so that the wind can not pass through, and thus has good wind protection and heat preservation characteristics.Since the advent of the membrane through continuous improvement, special treatment on the PTFE film, its fastness and durability greatly improved, after composite with other fabrics, widely used in the greenwood clothing, medical clothing, leisure clothing, fire control, chemical protective, antivirus, flooding operation, such as special protective clothing, outdoor sports clothing, shoes and hats, gloves and other accessories as well as sleeping bags, tents and other materials

Technical parameters are as follows:

Thickness: um 20-50 um

Moisture permeability: 16000g/㎡•24hr

Hydrostatic pressure: 6000mm

Extreme uv resistance: 97 highest

Width: 1700 mm or less

G: 5-10 g/m2

 

3. teflon bubble point film

It with polytetrafluoroethylene (ptfe) as raw material, after puffing stretch forming a kind of microporous membrane, the membrane with a special process combined with on all kinds of fabric and base material, become a new type of filtration material, the membrane pore size is small, about 0.2 to 0.5 mu m, uniform distribution, porosity, while maintain the air circulation, can filter all of the dust particles, including bacteria, achieve the goal of advanced purification and ventilation, it is widely used in pharmaceutical, biochemical, microelectronics and laboratory consumables, etc.

Technical parameters:

Thickness width bubble point

1600mm ≥1kg/cm2 (5.3m/s 127Pa)